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+The Project Gutenberg EBook of Scientific American Supplement, No. 365,
+December 30, 1882, by Various
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Scientific American Supplement, No. 365, December 30, 1882
+
+Author: Various
+
+Release Date: July 6, 2006 [EBook #18763]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN ***
+
+
+
+
+Produced by David King, Juliet Sutherland and the Online
+Distributed Proofreading Team at http://www.pgdp.net
+
+
+
+
+
+[Illustration]
+
+
+
+
+SCIENTIFIC AMERICAN SUPPLEMENT NO. 365
+
+
+
+
+NEW YORK, DECEMBER 30, 1882.
+
+Scientific American Supplement. Vol. XIV., No. 365.
+
+Scientific American established 1845
+
+Scientific American Supplement, $5 a year.
+
+Scientific American and Supplement, $7 a year.
+
+       *       *       *       *       *
+
+
+
+
+TABLE OF CONTENTS.
+
+
+I.    ENGINEERING AND MECHANICS.--Louis Favre, Constructor
+      of the St. Gothard Tunnel.--2 figures.--Portrait and
+      monument at Turin to commemorate the tunneling of the
+      Alps                                                      5817
+
+      The New Harbor of Vera Cruz.--New artificial harbor
+      for Vera Cruz.--Capt. Eads's plan.--1 figure.--Plan
+      of harbor and improvement                                 5818
+
+      Cost of Power to Make Flour                               5818
+
+      Driving gear Mechanism for Lift Hammers.--2 figures       5819
+
+      De Junker and Ruh's Machine for Cutting Annular
+      Wheels.--3 figures                                        5819
+
+      Recent Hydraulic Experiments.--Results of experiments
+      on the flow of water in the Ganges Canal                  5819
+
+      The Germ: Shall It be Retained in Flour? By Arthur
+      Atkins                                                    5820
+
+      Wheat Tests                                               5820
+
+II.   TECHNOLOGY AND CHEMISTRY.--Apparatus for Manufacturing
+      Gaseous or Aerated Beverages.--11 figures.--Bicarbonate
+      of soda apparatus. Generator. Washer.--Suction
+      pump.--Saturator.--Apparatus for using carbonate of
+      lime.--Apparatus completely mechanical in operation       5815
+
+      Detection and Estimation of Fusel Oil                     5816
+
+      On Silicon.--Curious formation of silicide of platinum    5816
+
+      Stannous Nitrates.--The formation of explosive
+      compounds in machines by the corrosion of bronze and
+      tin solder                                                5816
+
+      Metallic Thorium. By L.F. Nilson                          5816
+
+      Friedrich Wöhler.--Obituary notice of the great German
+      chemist                                                   5816
+
+      Apparatus for Printing by the Blue Process. By
+      Channing Whitaker.--3 figures                             5820
+
+III.  ELECTRICITY, LIGHT, HEAT, ETC.--Spectrum Gratings         5822
+
+      A New Pocket Opera Glass.--4 figures                      5822
+
+      Atoms, Molecules, and Ether Waves. By JOHN TYNDALL.
+      Action of heat and light on molecules.--Heat as an
+      agent in exploring molecular conditions.--The results
+      of a recent incursion into the extra-sensible world
+      of atoms and molecules                                    5823
+
+      Apparatus for Measuring Electricity at the Upper
+      School of Telegraphy. By E. MERCADIER.--5 figures.
+      Constant vibrator.--The Electrical tuning fork.
+      Arrangement for testing electric piles.--Very rapid
+      electric tuning fork.--A vibrating micrometer             5824
+
+IV.   NATURAL HISTORY.--Our Origin as a Species. By RICHARD
+      OWEN.--The Neanderthal skull.--Differential characters
+      between the lowest _Homo_ and the highest _Simia_         5825
+
+      The Aba or Odika. By Dr. W.H. BACHELER.--A remarkable
+      tree of West Africa                                       5826
+
+      California Cedars                                         5826
+
+       *       *       *       *       *
+
+
+
+
+APPARATUS FOR MANUFACTURING GASEOUS OR AERATED BEVERAGES.
+
+
+The apparatus employed at present for making gaseous beverages are
+divided into two classes--intermittent apparatus based on chemical
+compression, and continuous ones based on mechanical compression.
+
+The first are simple in appearance and occupy small space, but their use
+is attended with too great inconveniences and losses to allow them to be
+employed in cases where the manufacture is of any extent, so the
+continuous apparatus are more and more preferred by those engaged in the
+industry.
+
+Continuous apparatus, however, other than those that we now propose to
+occupy ourselves with, are not without some defects, for the gas is
+produced in them intermittingly and at intervals, and more rapidly than
+it is used, thus necessitating the use of a gasometer, numerous and
+large washers, complicated piping, and, besides, of an acid cock.
+
+To get rid of such drawbacks, it became necessary to seek a means of
+rendering the production of the gas continuous, and of regulating it
+automatically without the aid of the operator. Mr. Mondollot has
+obtained such a result through a happy modification of the primitive
+system of the English engineer Bramah. He preserves the suction and
+force pump but, while applying it to the same uses, he likewise employs
+it, by the aid of a special arrangement, so as to distribute the
+sulphuric acid automatically over the chalk in the generator, and to
+thus obtain a regular and continuous disengagement of carbonic acid gas.
+The dangers and difficulties in the maneuver of an acid cock are
+obviated, the gasometer and its cumbersome accessories are dispensed
+with, and the purification is more certain, owing to the regularity with
+which the gas traverses the washers.
+
+In the accompanying plate we have figured three types of these
+apparatus. The first that we shall describe is arranged for the use of
+bicarbonate of soda. This apparatus consists (1) of a _generator_, C D,
+(2) of a double _washer_ G G, (3) of a _suction pump_, P, and (4) of a
+_saturator_, S (See Figs 1 to 9).
+
+_The Generator._--This consists of a cylindrical leaden receptacle, D,
+on the bottom of which rests a leaden bell containing apertures, c, at
+its base. A partition, c, into which is screwed a leaden tube, C,
+containing apertures divides the interior of the bell into two
+compartments. The upper of these latter is surmounted by a mouth, B,
+closed by a clamp, and through which the bicarbonate of soda is
+introduced. A definite quantity of water and sulphuric acid having been
+poured into the receptacle, D, a level tends to take place between the
+latter and the bell, C, the liquid passing through the apertures. But
+the acidulated water, coming in contact with the soda, sets free
+carbonic acid gas, which, having no exit, forces the water back and
+stops the production of gas until the apparatus is set in motion. At
+this moment, the suction of the pump causes a new inflow of acidulated
+water upon the soda, from whence another disengagement of gas, and then
+a momentary forcing of the water, whose level thus alternately rises and
+falls and causes a continuous production of gas proportionate with the
+suction of the pump.
+
+The consumption of soda and acid is about 2 kilogrammes each for
+charging 100 siphons or 150 bottles. The bicarbonate is known to be used
+up when the liquid in the generator is seen to descend to the bottom of
+the water level, n, fixed to the vessel, D.
+
+_The Washer_ (Figs 1 and 4)--The gas, on leaving the generator, enters
+the washer through a bent copper pipe, R. The washer is formed of two
+ovoid glass flasks G G, mounted on a bronze piece, L, to which they are
+fixed by screw rings, l, of the same metal. The two flasks, G G,
+communicate with each other only through the tinned-copper tube q,
+which is held in the mounting q, of the same metal. This latter is
+screwed into the piece, L, and contains numerous apertures, through
+which the gas coming in from the pipe, R, passes to reach the upper
+flask, G. The gas is washed by bubbling up through water that has been
+introduced through the cock, R. After it has traversed both flasks, it
+escapes through the copper pipe, p, into which it is sucked by the
+pump, P.
+
+_The Pump_ (Figs 1, 5 and 6)--This consists of a cylindrical chamber, P,
+of bronze, bolted to a bracket on the frame, and cast in a piece, with
+the suction valve chamber, P, in which the valve, p, plays. It is
+surmounted by the distributing valve chamber P². This latter is held
+by means of two nuts screwed on to the extremity of the rods, p³,
+connected with the shell, E, of the distributing-cock, E. In the shell,
+E, terminates, on one side, the pipe, p, through which enters the gas
+from the washer, and, on the other, the pipe i, that communicates with
+a feed-reservoir not shown in the cuts. The cock E, permits of the
+simultaneous regulation of the entrance of the gas and water. Its
+position is shown by an index e, passing over a graduated dial, _e¹_.
+From the distributing valve chamber, P² the pipe, s, leads the
+mixture of water and gas under pressure into
+
+_The Saturator_, S (Figs 1, 7 and 9)--This consists of a large copper
+vessel, s, affixed to the top of the frame through the intermedium of
+a bronze collar h, and a self closing bottom H. This latter is
+provided with two pipes, one of which, s, leads the mixture of water
+and carbonic acid forced by the pump, and the other, b, communicates
+with the siphons or bottles to be filled. The pipe, b, is not affixed
+directly to the bottom, but is connected therewith through the
+intermedium of a cock, r. The object of the broken form of this pipe
+is to cause the pressure to act according to the axis of the screw, r,
+which is maneuvered by the key, r².
+
+The water under pressure, having been forced into the vessel, S, is
+submitted therein to an agitation that allows it to dissolve a larger
+quantity of gas. Such agitation is produced by two pairs of paddles, J
+J, mounted at the extremity of an axle actuated by the wheel, A, through
+the intermedium of gearings, g and g.
+
+The course of the operation in the saturator may be followed by an
+inspection of the water level, n, seen at the front and side in Figs.
+2 and 3. This apparatus, in which the pressure reaches 4 to 6
+atmospheres in the manufacture of Seltzer water or gaseous lemonade in
+bottles, and from 10 to 12 atmospheres in that of Seltzer water in
+siphons, is provided also with a pressure gauge, m, and a safety
+valve, both screwed, as is also the tube, n², into a sphere, S, on
+the top of the saturator.
+
+_Apparatus for Using Carbonate of Lime_ (Figs 2, 3, and 10)--When chalk
+is acted upon by sulphuric acid, there is formed an insoluble sulphate
+which, by covering the chalk, prevents the action of the acid from
+continuing if care be not taken to constantly agitate the materials.
+This has led to a change in the arrangement of the generator in the
+apparatus designed for the use of chalk.
+
+It consists in this case of a leaden vessel, D, having a hemispherical
+bottom set into a cylindrical cast iron base, K, and of an agitator
+similar to that shown in Fig. 11, for keeping the chalk in suspension in
+the water. These latter materials are introduced through the mouth, B
+(Fig. 3). Then a special receptacle, C, of lead, shown in detail in Fig.
+10, and the cock, c, of which is kept closed, is filled with sulphuric
+acid. The acid is not introduced directly into the vessel, C, but is
+poured into the cylinder, C, whose sides contain numerous apertures
+which prevent foreign materials from passing into the siphon tube c,
+and obstructing it.
+
+To put the apparatus in operation, the acid cock, c, is opened and the
+wheel, A, is turned, thus setting in motion both the pump piston, P, and
+the agitator, within S and D. Then the play of the pump produces a
+suction in the washers and from thence in the generator and causes the
+acid in the vessel, C, to flow into the generator through the leaden
+siphon tubes, c. Coming in contact with the chalk in suspension, the
+acid produces a disengagement of gas which soon establishes sufficient
+pressure to stop the flow of the acid and drive it back into the siphon
+tube. The play of the pump continuing, a new suction takes place and
+consequently a momentary flow of acid and a new disengagement of gas.
+Thus the production of the latter is continuous, and is regulated by the
+very action of the pump, without the operator having to maneuver an
+acid-cock. The latter he only has to open when he sets the apparatus in
+operation, and to close it when he stops it.
+
+The arrangement of the washer is the same as in the preceding apparatus,
+save that a larger cylindrical copper reservoir, G', is substituted for
+the lower flask. The pump and saturator offer nothing peculiar.
+
+A bent tube, u, which communicates with the generator, D, on one side,
+and with a cylindrical tube, V, ending in a glass vessel on the other,
+serves as a safety-valve for both the generator and the acid vessel.
+
+The consumption of chalk is about 2.5 kilogrammes, and the same of acid,
+for charging 100 siphons or 150 bottles. The apparatus shown in the
+figure is capable of charging 600 siphons or 900 bottles per day.
+
+_An Apparatus Completely Mechanical in Operation_ (Fig. 11).--This
+apparatus consists of two very distinct parts. The saturator, pump, and
+driving shaft are supported by a hollow base, in whose interior are
+placed a copper washer and the water-inlet controlled by a float-cock.
+This part of the apparatus is not shown in the plate. The generator,
+partially shown in Fig. 11, is placed on a base of its own, and is
+connected by a pipe with the rest of the apparatus. It consists of two
+similar generators, D, made of copper lined with lead, and working
+alternately, so as to avoid all stoppages in the manufacture when the
+materials are being renewed. The pipe, d, connecting the two parts of
+the apparatus forks so as to lead the gas from one or the other of the
+generators, whence it passes into the copper washer within the base,
+then into the glass indicating washer, and then to the pump which forces
+it into the saturator.
+
+Each of the generators communicates by special pipes, a, with a single
+safety vessel, V, that operates the same as in the preceding apparatus.
+The agitator, Q, is of bronze, and is curved as shown in Fig. 11.
+
+The production of this type of apparatus is dependent upon the number of
+siphons that can be filled by a siphon filler working without
+interruption.--_Machines, Outils et Appareils._
+
+       *       *       *       *       *
+
+
+
+
+DETECTION AND ESTIMATION OF FUSEL OIL.
+
+
+Until quite recently we have had no accurate method for the
+determination of fusel oil in alcohol or brandy. In 1837 Meurer
+suggested a solution of one part of silver nitrate in nine parts of
+water as a reagent for its detection, stating that when added to alcohol
+containing fusel oil, a reddish brown color is produced, and in case
+large quantities are present, a dark brown precipitate is formed. It was
+soon found, however, that other substances than amyl alcohol produce
+brown colored solutions with silver nitrate; and Bouvier[1] observed
+that on adding potassium iodide to alcohol containing fusel oil, the
+solution is colored yellow, from the decomposition of the iodide.
+Subsequently Böttger[2] proved that potassium iodide is not decomposed
+by pure amyl alcohol, and that the decomposition is due to the presence
+of acids contained in fusel oil. More accurate results are obtained by
+using a very dilute solution of potassium permanganate, which is
+decomposed by amyl alcohol much more rapidly than by ethyl alcohol.
+
+    [Footnote 1: Zeitschrift f. Anal. Chem. xi., 343.]
+
+    [Footnote 2: Dingler's Polytech. Jour., ccxii., 516.]
+
+Depré[3] determines fusel oil by oxidizing a definite quantity of the
+alcohol in a closed vessel with potassium bichromate and sulphuric acid.
+after removal of excess of the oxidizing reagents, the organic acids are
+distilled, and, by repeated fractional distillation, the acetic acid is
+separated as completely as possible. The remaining acids are saturated
+with barium hydroxide, and the salts analyzed; a difference between the
+percentage of barium found and that of barium in barium acetate proves
+the presence of fusel oil, and the amount of difference gives some idea
+of its quantity. Betelli[4] dilutes 5 c.c. of the alcohol to be tested
+with 6 to 7 volumes of water, and adds 15 to 20 drops of chloroform and
+shakes thoroughly. If fusel oil is present, its odor may be detected by
+evaporating the chloroform; or, by treatment with sulphuric acid and
+sodium acetate, the ether is obtained, which can be readily recognized.
+Jorissen[5] tests for fusel oil by adding 10 drops of colorless aniline
+and 2 to 3 drops of hydrochloric acid to 10 c.c. of the alcohol. In the
+presence of fusel oil a red color is produced within a short time, which
+can be detected when not more than 0.1 per cent. is present. But
+Foerster[6] objects to this method because he finds the color to be due
+to the presence of furfurol, and that pure amyl alcohol gives no color
+with aniline and hydrochloric acid.
+
+    [Footnote 3: Pharm. J. Trans. [3] vi., 867.]
+
+    [Footnote 4: Berichte d. Deutschen Chem. Gesellsch., viii., 72.]
+
+    [Footnote 5: Pharm. Centralhalle, xxii., 3.]
+
+    [Footnote 6: Berichte d. Deutsch. Chem. Gesellsch., xv., 230.]
+
+Hager[7] detects fusel oil as follows: If the spirit contains more than
+60 per cent. of alcohol, it is diluted with an equal volume of water and
+some glycerine added, pieces of filter paper are then saturated with the
+liquid and exposed to the After the evaporation of the alcohol, the odor
+of the fusel oil can be readily detected. For the quantitative
+determination he distills 100 c.c. of the alcohol in a flask of 150 to
+200 c.c. capacity connected with a condenser, and so arranged that the
+apparatus does not extend more than 20 cm. above the water bath. This
+arrangement prevents the fusel oil from passing over. If the alcohol is
+stronger than 70 per cent., and the height of the distillation apparatus
+is not more than 17 cm., the residue in the flask may be weighed as
+fusel oil. With a weaker alcohol, or an apparatus which projects further
+out of the water bath, the residual fusel oil is mixed with water. It
+can, however, be separated by adding strong alcohol and redistilling, or
+by treating with ether, which dissolves the amyl alcohol, and
+distilling, the temperature being raised finally to 60°.
+
+    [Footnote 7: Pharm. Centralhalle, xxii., 236.]
+
+Marquardt,[8] like Betelli, extracts the fusel oil from alcohol by means
+of chloroform, and by oxidation converts it into valeric acid. From the
+quantity of barium valerate found he calculates the amount of amyl
+alcohol present in the original solution; 150 c.c. of the spirit, which
+has been diluted so as to contain 12 to 15 per cent. of alcohol, are
+shaken up thoroughly with 50 c.c. of chloroform, the aqueous layer drawn
+off, and shaken with a fresh portion of chloroform. This treatment is
+repeated several times. The extracts are then united, and washed
+repeatedly with water. The chloroform, which is now free from alcohol
+and contains all the fusel oil, is treated with a solution of 5 grammes
+of potassium bichromate in 30 grammes of water and 2 grammes of
+sulphuric acid, and then heated in a closed flask for six hours on a
+water bath at 85°. The contents of the flask are then distilled, the
+distillate saturated with barium carbonate, and the chloroform
+distilled; the residue is evaporated to a small volume, the excess of
+barium carbonate filtered off, and the filtrate evaporated to dryness
+and weighed. The residue is dissolved in water, a few drops of nitric
+acid added, and the solution divided into two portions. In the first
+portion the barium is determined; in the second the barium chloride. The
+total per cent. of barium minus that of barium chloride gives the amount
+present as barium valerate, from which is calculated the per cent. of
+amyl alcohol. By this process the author has determined one part of
+fusel oil in ten thousand of alcohol. To detect very minute quantities
+of fusel oil, the chloroform extracts are treated with several drops of
+sulphuric acid and enough potassium permanganate to keep the solution
+red for twenty-four hours. If allowed to stand in a test tube, the odor
+of valeric aldehyde will first be noticed, then that of amyl valerate,
+and lastly that of valeric acid.--_Amer. Chem. Journal._
+
+    [Footnote 8: Berichte d. Deutsch. Chem. Gesellsch., xv., 1,370
+    and 1,663.]
+
+       *       *       *       *       *
+
+
+
+
+ON SILICON.
+
+
+It is known that platinum heated in a forge fire, in contact with
+carbon, becomes fusible. Boussingault has shown that this is due to the
+formation of a silicide of platinum by means of the reduction of the
+silica of the carbon by the metal. MM. P. Schützenberger and A. Colson
+have produced the same phenomenon by heating to white heat a slip of
+platinum in the center of a thick layer of lampblack free from silica.
+
+The increase in weight of the metal and the augmentation of its
+fusibility were found to be due, in this case also, to a combination
+with silicon. As the silicon could not come directly from the carbon
+which surrounded the platinum, MM. Schützenberger and Colson have
+endeavored to discover under what form it could pass from the walls of
+the crucible through a layer of lampblack several centimeters in
+thickness, in spite of a volatility amounting to almost nothing under
+the conditions of the experiment. They describe the following
+experiments as serving to throw some light upon the question:
+
+1. A thin slip of platinum rolled in a spiral is placed in a small
+crucible of retort carbon closed by a turned cover of the same material.
+This is placed in a second larger crucible of refractory clay, and the
+intervening space filled with lampblack tightly packed. The whole is
+then heated to white heat for an hour and a half in a good wind furnace.
+After cooling, the platinum is generally found to have been fused into a
+button, with a marked increase in weight due to taking up silicon, which
+has penetrated in the form of vapor through the walls of the interior
+crucible.
+
+2. If, in the preceding experiment, the lampblack be replaced by a
+mixture of lampblack and rutile in fine powder, the slip of platinum
+remains absolutely intact, and does not change in weight. Thus the
+titaniferous packing recommended by Sainte-Claire Deville for preventing
+the access of nitrogen in experiments at high temperatures also prevents
+the passage of silicon. A mixture of carbon and finely divided iron is,
+on the contrary, ineffectual. These facts seem to indicate that nitrogen
+plays a part in the transportation of the silicon, as this is only
+prevented by the same means made use of in order to prevent the passage
+of nitrogen.
+
+3. The volatility of free silicon at a high temperature is too slight to
+account for the alteration of the platinum at a distance. This can be
+shown by placing several decigrammes of crystallized silicon on the
+bottom of a small crucible of retort carbon, covering the silicon with a
+small flat disk of retort carbon upon which is placed the slip of
+platinum. The crucible, closed by its turned cover, is then enveloped in
+a titaniferous packing and kept at a brilliant white heat for an hour
+and a half. The metal is found to have only very slightly increased in
+weight, and its properties remain unaltered. This experiment was
+repeated several times with the same result. If, however, the
+crystallized silicon be replaced by powdered calcined silica, the
+platinum, placed upon the carbon disk, fuses and increases in weight,
+while the silica loses weight. The theory of these curious phenomena is
+very difficult to establish on account of the high temperatures which
+are necessary for their manifestation, but it may be concluded, at
+present, that nitrogen and probably oxygen also play some part in the
+transportation of the silicon across the intervening space, and that the
+carbosilicious compounds recently described by MM. Schützenberger and
+Colson also take part in the phenomenon.--_Comptes Rendus_, xciv.,
+1,710.--_Amer. Chem. Journal._
+
+       *       *       *       *       *
+
+
+
+
+STANNOUS NITRATES.
+
+
+At the Royal Powder Works at Spandau, Prussia, frequent ignition of the
+powder at a certain stage of the process led to an examination of the
+machinery, when it was found that where, at certain parts, bronze pieces
+which were soldered were in constant contact with the moist powder, the
+solder was much corroded and in part entirely destroyed, and that in the
+joints had collected a substance which, on being scraped out with a
+chisel, exploded with emission of sparks. It was suspected that the
+formation of this explosive material was in some way connected with the
+corrosion of the solder, and the subject was referred for investigation
+to Rudolph Weber, of the School of Technology, at Berlin. The main
+results of his investigation are here given.
+
+The explosive properties of the substance indicated a probable
+nitro-compound of one of the solder metals (tin and lead), and as the
+lead salts are more stable and better understood than those of tin, it
+was resolved to investigate the latter, in hope of obtaining a similar
+explosive compound. Experiments on the action of moist potassium nitrate
+on pure tin led to no result, as no explosive body was formed. Stannous
+nitrate, Sn(NO_{3})_{2}, formed by the action of dilute nitric acid on
+tin, has long been known, but only in solution, as it is decomposed on
+evaporating. By adding freshly precipitated moist brown stannous oxide
+to cool nitric acid of sp. gr. 1.20, as long as solution occurred, and
+then cooling the solution to -20°, Weber obtained an abundance of
+crystals of the composition Sn(NO_{3})_{2} + 20H_{2}O. They resemble
+crystals of potassium chlorate. They cannot be kept, as they liquefy at
+ordinary temperatures. An insoluble _basic_ salt was obtained by
+digesting an excess of moist stannous oxide in solution of stannous
+nitrate, or by adding to a solution of stannous nitrate by degrees, with
+constant stirring, a quantity of sodium carbonate solution insufficient
+for complete precipitation. Thus obtained, the basic salt, which has the
+composition Sn_{2}N_{2}O_{7}, is a snow-white crystalline powder, which
+is partially decomposed by water, and slowly oxidized by long exposure
+to the air, or by heating to 100°. By rapid heating to a higher
+temperature, as well as by percussion and friction, it explodes
+violently, giving off a shower of sparks. This compound is also formed
+when a fine spray of nitric acid (sp. gr. 1.20) is thrown upon a surface
+of tin or solder. It is also formed when tin or solder is exposed to the
+action of a solution of copper nitrate, and thus formed presents the
+properties already described.
+
+In this, then, we have a probable cause of the explosions occurring in
+the powder works; but the explanation of the formation of the substance
+is wanting, as potassium nitrate was shown not to give an explosive
+substance with tin. A thin layer of a mixture of sulphur and potassium
+nitrate was placed between sheets of tin and copper foil, and allowed to
+stand, being kept constantly moist. After a time the copper was found to
+have become coated with sulphide, while the tin was largely converted
+into the explosive basic nitrate. The conditions are obviously the same
+as those found in the powder machinery, where bronze and tin solder are
+constantly in contact with moist gunpowder. The chemical action is
+probably this: the sulphur of the powder forms, with the copper of the
+bronze, copper sulphide; this is oxidized to sulphate, which reacts with
+the niter of the powder, forming potassium sulphate and copper nitrate;
+the latter, as shown above, then forms with the tin of the solder the
+explosive basic nitrate, which, being insoluble, gradually collects in
+the joints, and finally leads to an explosion.--_Journal für Praktische
+Chemie._
+
+       *       *       *       *       *
+
+
+
+
+METALLIC THORIUM.
+
+By L.F. NILSON.
+
+
+The density of thorium as obtained by reducing the anhydrous chloride by
+means of sodium was found by Chydenius, 7.657 to 7.795. The author has
+obtained metallic thorium by heating sodium with the double anhydrous
+thorium potassium chloride, in presence of sodium chloride in an iron
+crucible. After treating the residue with water there remains a grayish,
+heavy, sparkling powder, which under the microscope appears to consist
+of very small crystals. Metallic thorium is brittle and almost
+infusible; the powder takes a metallic luster under pressure, is
+permanent in the air at temperatures up to 120°, takes fire below a red
+heat either in air or oxygen, and burns with a dazzling luster, leaving
+a residue of perfectly white thoria. If heated with chlorine, bromine,
+iodine, and sulphur, it combines with them with ignition. It is not
+attacked by water, cold or hot. Dilute sulphuric acid occasions the
+disengagement of hydrogen, especially if heated, but the metal is acted
+on very slowly. Concentrated sulphuric acid with the aid of heat attacks
+the metal very slightly, evolving sulphurous anhydride. Nitric acid,
+strong or weak, has no sensible action. Fuming hydrochloric acid and
+_aqua regia_ attack thorium readily, but the alkalies are without
+action. The metal examined by the author behaves with the reagents in
+question the same as did the specimens obtained by Berzelius. The mean
+specific gravity of pure thorium is about 11. Hence it would seem that
+the metal obtained by Chydenius must have contained much foreign matter.
+The specific gravity of pure thoria is 10.2207 to 10.2198. The
+equivalent and the density being known, we may calculate the atomic
+volume. If we admit that the metal is equivalent to 4 atoms of hydrogen,
+we obtain the value 21.1. This number coincides with the atomic volumes
+of zirconium (21.7), cerium (21.1), lanthanum (22.6), and didymium
+(21.5). This analogy is certainly not due to chance; it rather confirms
+the opinion which I have put forward in connection with my researches on
+the selenites, on certain chloro-platinates and chloro-platinites, etc.,
+that the elements of the rare earths form a series of quadrivalent
+metals.
+
+       *       *       *       *       *
+
+[AMERICAN CHEMICAL JOURNAL.]
+
+
+
+
+FRIEDRICH WÖHLER.
+
+
+No one but a chemist can appreciate the full significance of the brief
+message which came to us a month ago without warning--"Wöhler is dead!"
+What need be added to it? No chemist was better known or more honored
+than Wöhler, and none ever deserved distinction and honor more than he.
+His life was made up of a series of brilliant successes, which not only
+compelled the admiration of the world at large, but directed the
+thoughts of his fellow workers, and led to results of the highest
+importance to science.
+
+It is impossible in a few words to give a correct account of the work of
+Wöhler, and to show in what way his life and work have been of such
+great value to chemistry. Could he himself direct the preparation of
+this notice, the writer knows that his advice would be, "Keep to the
+facts." So far as any one phrase can characterize the teachings of
+Wöhler, that one does it; and though enthusiasm prompts to eulogy, let
+us rather recall the plain facts of his life, and let them, in the main,
+speak for themselves.[1]
+
+    [Footnote 1: See Kopp's "Geschichte der Chemie," iv., 440.]
+
+He was born in the year 1800 at Eschersheim, a village near
+Frankfort-on-the-Main. From his earliest years the study of nature
+appears to have been attractive to him. He took great delight in
+collecting minerals and in performing chemical and physical experiments.
+While still a boy, he associated with a Dr. Buch, of Frankfort, and was
+aided by this gentleman, who did what he could to encourage in the young
+student his inclination toward the natural sciences. The first paper
+which bears the name of Wöhler dates from this period, and is upon the
+presence of selenium in the iron pyrites from Kraslitz. In 1820 he went
+to the University of Marburg to study medicine. While there he did not,
+however, neglect the study of chemistry. He was at that time
+particularly interested in an investigation on certain cyanogen
+compounds. In 1821 he went to Heidelberg, and in 1823 he received the
+degree of Doctor of Medicine. L. Gmelin became interested in him, and it
+was largely due to Gmelin's influence that Wöhler gave up his intention
+of practicing medicine, and concluded to devote himself entirely to
+chemistry. For further instruction in his chosen science, Wöhler went to
+Stockholm to receive instruction from Berzelius, in whose laboratory he
+continued to work from the fall of 1823 until the middle of the
+following year. Only a few years since, in a communication entitled
+"Jugenderinnerungen eines Chemikers," he gave a fascinating account of
+his journey to Stockholm and his experiences while working with
+Berzelius. On his return to Germany, he was called to teach chemistry in
+the recently founded municipal trade school (Gewerbschule) at Berlin. He
+accepted the call, and remained in Berlin until 1832, when he went to
+Cassel to live. In a short time he was called upon to take part in the
+direction of the higher trade school at Cassel. He continued to teach
+and work in Cassel until 1836, when he was appointed Professor of
+Chemistry in Göttingen. This office he held at the time of his death,
+September 23, 1882.
+
+In 1825 Wöhler became acquainted with Liebig, and an intimate friendship
+resulted, which continued until the death of Liebig, a few years ago.
+Though they lived far apart, they met during the vacations at their
+homes, or traveled together. Many important investigations were
+conceived by them as they talked over the problems of chemistry, and
+many papers appeared under both their names, containing the results of
+their joint work. Among such papers may be mentioned: "On Cyanic Acid"
+(1830); "On Mellithic Acid" (1830); "On Sulphotartaric Acid" (1831); "On
+Oil of Bitter Almonds, Benzoic Acid, and Related Compounds" (1832); "On
+the Formation of Oil of Bitter Almonds from Amygdalin" (1837); and "On
+Uric Acid" (1837).
+
+Of the papers included in the above list, the two which most attract
+attention are those "On the Oil of Bitter Almonds" and "On Uric Acid."
+In the former it was shown for the first time that in analogous carbon
+compounds there are groups which remain unchanged, though the compounds
+containing them may, in other respects, undergo a variety of changes.
+This is the conception of radicals or residues as we use it at the
+present day. It cannot be denied that this conception has done very much
+to simplify the study of organic compounds. The full value of the
+discovery was recognized at once by Berzelius, who, in a letter to the
+authors of the paper, proposed that they should call their radical proin
+or orthrin (the dawn of day), for the reason that the assumption of its
+existence might be likened to the dawn of a new day in chemistry. The
+study of this paper should form a part of the work of every advanced
+student of chemistry. It is a model of all that is desirable in a
+scientific memoir. The paper on uric acid is remarkable for the number
+of interesting transformation products described in it, and the skill
+displayed in devising methods for the isolation and purification of the
+new compounds. Comparatively little has been added to our knowledge of
+uric acid since the appearance of the paper of Liebig and Wöhler.
+
+It would lead too far to attempt to give a complete list of the papers
+which have appeared under the name of Wöhler alone. In 1828 he made the
+remarkable discovery that when an aqueous solution of ammonium cyanate,
+CNONH_{4}, is evaporated, the salt is completely transformed into urea,
+which has the same percentage composition. It would be difficult to
+exaggerate the importance of this discovery. That a substance like urea,
+which up to that time had only been met with as a product of processes
+which take place in the animal body, should be formed in the laboratory
+out of inorganic compounds, appeared to chemists then to be little less
+than a miracle. To-day such facts are among the commonest of chemistry.
+The many brilliant syntheses of well-known and valuable organic
+compounds which have been made during the past twenty years are results
+of this discovery of Wöhler.
+
+In 1823 he published a paper on secretion, in the urine, of substances
+which are foreign to the animal organism, but which are brought into the
+body. He discovered the transformation of neutral organic salts into
+carbonates by the process of assimilation.
+
+In 1832 he investigated the dimorphism of arsenious acid and antimony
+oxide. In 1841 he made the discovery that dimorphous bodies have
+different fusing points, according as they are in the crystallized or
+amorphous condition.
+
+Among the more remarkable of his investigations in inorganic chemistry
+are those on methods for the preparation of potassium (1823); on
+tungsten compounds (1824); the preparation of aluminum (1827); of
+glucinum and yttrium (1828). In 1856, working with Ste. Claire Deville,
+he discovered crystallized boron.
+
+Analytical methods were improved in many ways, and excellent new methods
+were introduced by him. Further, he did a great deal for the improvement
+of the processes of applied chemistry.
+
+With Liebig he was associated in editing the "Annalen der Chemie and
+Pharmacie" and the "Handwörterbuch der Chemie." He wrote a remarkably
+useful and popular "Grundriss der Chemie." The part relating to
+inorganic chemistry appeared first in 1831, and was in use until a few
+years ago, when Fittig wrote his "Grundriss" on the same plan, a work
+which supplanted its prototype.
+
+The above will serve to give some idea of the great activity of Wöhler's
+life, and the fruitfulness of his labors. While thus contributing
+largely by his own work directly to the growth of chemistry, he did
+perhaps as much in the capacity of teacher. Many of the active chemists
+of the present day have enjoyed the advantages of Wöhler's instruction,
+and many can trace their success to the impulse gathered in the
+laboratory at Göttingen. The hand of the old master appears in
+investigations carried on to-day by his pupils.
+
+Wöhler's was not a speculative mind. He took very little part in the
+many important discussions on chemical theories which engaged the
+attention of such men as Dumas, Gerhardt, Berzelius, and Liebig, during
+the active period of his life. He preferred to deal with the facts as
+such; and no one ever dealt with the facts of chemistry more
+successfully. He had a genius for methods which has never been equaled.
+The obstacles which had baffled his predecessors were surmounted by him
+with ease. He was in this respect a truly great man.
+
+Personally, Wöhler was modest and retiring. His life was simple and
+unostentatious. He had a kindly disposition, which endeared him to his
+students, to which fact many American chemists who were students at
+Göttingen during the time of Wöhler's activity can cordially testify. In
+short, it may be said deliberately that Wöhler, as a chemist and as a
+man, was a fit model for all of us and for those who will come after us.
+Though he has gone, his methods live in every laboratory. His spirit
+reigns in many; could it reign in all, the chemical world would be the
+better for it.
+
+I.R.
+
+       *       *       *       *       *
+
+
+
+
+LOUIS FAVRE, CONSTRUCTOR OF THE ST. GOTHARD TUNNEL.
+
+
+It is now already a year that the locomotive has been rolling over the
+St. Gothard road, crossing at a flash the distance separating Basle from
+Milan, and passing rapidly from the dark and damp defiles of German
+Switzerland into the sun lit plains of Lombardy. Our neighbors
+uproariously fêted the opening of this great international artery, which
+they consider as their personal and exclusive work, as well from a
+technical point of view as from that of the economic result that they
+had proposed to attain--the creation of a road which, in the words of
+Bismarck, "glorifies no other nation." As regards the piercing of the
+Gothard, the initiative does, in fact, belong by good right to the
+powerful "Iron Chancellor," so we have never dreamed of robbing Germany
+of the glory (and it is a true glory) of having created the second of
+the great transalpine routes, that open to European products a new gate
+to the Oriental world. It seems to us, however, that in the noisy
+concert of acclamations that echoed during the days of the fêtes over
+the inauguration of the line, a less modest place might have been made
+for those who, with invincible tenacity and rare talent, directed the
+technical part of the work, and especially those 15 kilometers of
+colossal boring--the great St. Gothard Tunnel, which ranks in the
+history of great public works side by side with the piercing of the
+Frejus, and the marvelous digging of Suez and Panama.
+
+We recall just now the names of those who, during nearly ten years, have
+contributed with entire disinterestedness to the completion of this
+colossal work. Over all stands a figure of very peculiar
+originality--that of M. Louis Favre, the general contractor of the great
+tunnel, whose name will remain attached to the creation of this work
+through the Helvetian Alps, like that of Sommeiller to the great tunnel
+of the Frejus, and that of De Lesseps to the artificial straits that
+henceforward join the oceans. Having myself had the honor of occupying
+the position of general secretary of the enterprise under consideration,
+I have been enabled to make a close acquaintance with the man who was so
+remarkable in all respects, and who, after passing his entire life in
+great public works, died like a soldier on the field of honor--in the
+depths of the tunnel.
+
+[Illustration: LOUIS FAVRE.]
+
+[Illustration: THE DOWNFALL OF THE TITANS, CONQUERED BY THE GENIUS OF
+MAN. (Monument at Turin to Commemorate the Tunneling of the Alps.)]
+
+I saw Favre, for the first time, in Geneva, in 1872, a few days after he
+had assumed the responsibility of undertaking the great work. He had
+been living since the war on his magnificent Plongeon estate, on the
+right bank of the lake. There was no need of dancing attendance in order
+to reach the contractor of the greatest work that has been accomplished
+up to the present time, for M. Favre was easy of access. We had scarcely
+passed five minutes together than we we were conversing as we often did
+later after an acquaintance of six years. After making known to him the
+object of my visit, the desire of being numbered among the _personnel_
+of his enterprise, the conversation quickly took that turn of
+mirthfulness that was at the bottom of Favre's character. "This is the
+first time," said he to me, laughing, "that I ever worked with Germans,
+and I had not yet struck the first blow of the pick on the Gothard when
+they began to quibble about our contract of the 8th of last August. Ah!
+that agreement of August 8th! How I had to change and re-change it,
+later on. If this thing continues, we shall have a pretty quarrel,
+considering that I do not understand a word of the multiple
+interpretations of their _charabia_. I ought to have mistrusted this.
+But you see I have remained inactive during the whole of this
+unfortunate war. I was not made for promenading in the paths of a
+garden, and I should have died of chagrin if such inaction had had to be
+prolonged. When one lives, as I have, for thirty years around lumber
+yards, it is difficult to accustom one's self to the sedentary and
+secluded life that I have led here for nearly two years."
+
+As he said, with just pride, Louis Favre had, indeed, before becoming
+the first contractor of public works in the world, lived for a long time
+in lumber yards. The years that so many other better instructed but less
+learned persons, who were afterward to gladly accept his authority, had
+given up to their studies, Favre had passed in the humble shop of his
+father, a carpenter at Chêne, a small village at a half league from
+Geneva. It soon becoming somewhat irksome for him in the village, he
+left the paternal workbench to start on what is called the "tour of
+France." He was then eighteen years of age. Three years afterward, he
+was undertaking small works. It was not long ere he was remarked by the
+engineers conducting the latter, and he was soon called to give his
+advice on all difficult questions. Between times, Favre had courageously
+studied the principal bases of such sciences as were to be useful to
+him. In the evening, he made up at the public school what was lacking in
+his early instruction; not that he hoped to make a complete study for an
+engineer, but only to learn the indispensable. He was, before all
+things, a practical man, who made up for the enforced insufficiency of
+his technical knowledge by a _coup d'oeil_ of surprising accuracy.
+Here it may be said to me that the piercing of the great St. Gothard
+Tunnel was accompanied by considerable loss. That is true, but it must
+be recalled also that this colossal work was accomplished amid the most
+insurmountable difficulties which ever presented themselves. In spite of
+this, the cost of the tunnel per running foot was also a third less than
+that of the great Mont Cenis Tunnel.
+
+When Favre undertook the St. Gothard, he already reckoned to his credit
+numerous victories in the domain of public works, especially in the
+construction of subterranean ones. The majority of tunnels of any length
+which, since the beginning of the establishment of railways, have been
+considered as works of some proportions (the Blaisy Tunnel, for
+instance), were executed by him, in addition to other open air works. So
+Favre reached the St. Gothard full of hope. The battle with the colossus
+did not displease him, and his courage and his confidence in the success
+of the work seemed to increase in measure as the circumstances
+surrounding the boring became more difficult. In the presence of the
+terrible inundation of the gallery of Airolo and the falling of
+aquiferous rocks, creating in the subterranean work so desperate a
+situation that a large number of very experienced engineers almost
+advised the abandonment of the works, Favre remained impassive. Amid the
+general apprehension, which, it may be readily comprehended, was felt in
+such a situation he made his confident and cheerful voice heard,
+reviving the ardor of all, and speaking disdainfully of "that
+insignificant Gothard, which would come out all right." The _personnel_
+of the enterprise were not the only ones, however, who were uneasy over
+the constantly occurring difficulties in the way of the work, for the
+company itself and the Swiss Federal Council made known to Favre their
+fears that the execution of the work would be delayed. He, however,
+calmed their fears, and exposed his projects to them, and the seances
+always ended by a vote of confidence in the future of the undertaking.
+Favre certainly did not dissimulate the difficulties that he should have
+to conquer, but he execrated those who were timorous and always tried to
+put confidence into those who surrounded him. But, singular phenomenon,
+he ended by deceiving himself and, at certain times, it would not have
+been easy to prove to him that the St. Gothard was not the most easy
+undertaking in the world. Those who have lived around him know the jokes
+that he sometimes made at the expense of poor Gothard, which paid him
+back with interest, however, and did not allow itself to be pierced so
+easy after all.
+
+Such confidence as existed in the first years, however, was not to exist
+for ever. The tunnel advanced, the heading deepened, but at the price of
+what troubles, and especially of how many expenses! Day by day one could
+soon count the probable deficit in the affair and the silent partners
+began to get a glimpse of the loss of the eight millions of securities
+that had had to be deposited with the Swiss Federal Council. For Favre
+personally the failure of the enterprise would have been ruin for his
+fortune was not so large as has been stated. To fears which Favre
+possessed more on account of the associates that he had engaged in the
+enterprise than for himself, came to join themselves those troubles with
+the Germans that he had spoken to me about on the first day. The St.
+Gothard Company, whose troubles are so celebrated, and whose inactivity
+lasted until the reconstruction of the affair, was seemingly undertaking
+to make Favre, who was directing the only work then in activity, bear
+all the insults that it had itself had to endure. And yet, amid these
+multiple cares, the contractor of the tunnel did not allow himself to
+become disheartened. Constantly at the breach he lived at his works,
+going from the gigantic adit of Goschenen to the inundated one of Anolo,
+constantly on the mountain, having no heed of the icy and perilous
+crossing, and passing days in the torrential rain that was flooding the
+tunnel. Who of us does not picture him in mind as he reached the inn at
+night, with his high boots still soaking wet, and his gray beard full of
+icicles to take his accustomed seat at the table, and, between courses,
+to tell some story full of mirth, some joke from the other works whence
+he had come, which made us laugh immoderately, and brought a smile to
+the faces of the German engineers.
+
+It is a singular coincidence that this confidence in his own work,
+despite all the struggles borne, was shared likewise by another man than
+Favre--by Germano Sommeiller, the creator of the Mont Cenis Tunnel. When
+the work of the first piercing of the Alps was yet in the period of
+attacks and incredulity, Sommeiller wrote his brother the following
+letter: "Always keep me posted my dear Leander, as to what the laughers
+are saying and remember the proverb that 'he will laugh well who laughs
+last!' The majority of the people, even engineers, are rubbing their
+hands in expectation of the colossal fiasco that awaits us, and it is
+for that that the envious keep somewhat silent. I will predict to you
+that as soon as success is assured everybody will mount to the house
+tops and say 'I told you so! It was an idea of my own!' What great
+geniuses are going to spring from the earth! I am in haste, so adieu,
+courage, energy, silence and especially cheerfulness! And especially
+cheerfulness!" Perhaps this cheerfulness of strong minds is the
+invincible weapon of those who, like Sommeiller and Favre, fight against
+apathy or the bad faith of their adversaries! Like Favre however
+Sommeiller had not the pleasure of being present at the consecration of
+his glory, for at the Mont Cenis banquet as at the St. Gothard the place
+reserved for the creator of the great work was empty.
+
+As disastrous as was the enterprise from a financial point of view what
+a triumph for Favre would have been the day on which he traversed from
+one end to the other that 15 kilometers of tunnel that he had walked
+over step by step since the first blow of the pick had struck the rock
+of the St. Gothard! But such a satisfaction was not to be reserved for
+him. Suddenly, on the 19th of July, 1879, less than seven years after
+the beginning of the work, and six months before the meeting of the
+adits, in the course of one of his visits to the tunnel Favre was
+carried off by the rupture of a blood vessel. A year before that epoch,
+I had left the enterprise, Favre having confided to me the general
+supervision over the manufacture of dynamite that he had undertaken at
+Varallo Pombia for the needs of his tunnel, but my friend M. Stockalper,
+engineer in chief of the Goschenen section, who accompanied Favre on his
+fatal subterranean excursion, has many a time recounted to me the sad
+details of his sudden death.
+
+For months before it must be said Favre had been growing old. The man of
+broad shoulders and with head covered with thick hair in which here and
+there a few silver threads showed themselves, and who was as straight as
+at the age of twenty years, had begun to stoop, his hair had whitened
+and his face had assumed an expression of sadness that it was difficult
+for him to conceal. As powerful as it was this character had been
+subjugated. The transformation had not escaped me. Often during the days
+that we passed together he complained of a dizziness that became more
+and more frequent. We all saw him rapidly growing old. On the 19th of
+July, 1879, he had entered the tunnel with one of his friends, a French
+engineer who had come to visit the work, accompanied by M. Stockalper.
+Up to the end of the adit he had complained of nothing, but, according
+to his habit, went along examining the timbers, stopping at different
+points to give instructions, and making now and then a sally at his
+friend, who was unused to the smell of dynamite. In returning he began
+to complain of internal pains. "My dear Stockalper," said he, "take my
+lamp, I will join you." At the end of ten minutes not seeing him return,
+M. Stockalper exclaimed, "Well! M. Favre, are you coming?" No answer.
+The visitor and engineer retraced their steps, and when they reached
+Favre he was leaning against the rocks with his head resting upon his
+breast. His heart had already ceased to beat. A train loaded with
+excavated rock was passing and on this was laid the already stiff body
+of him who had struggled up to his last breath to execute a work all
+science and labor. A glorious end, if ever there was one!
+
+Favre died in the full plenitude of his forces at less than fifty four
+years of age, and I can say, without fear of contradiction, that he was
+universally and sincerely regretted by all those who had worked at his
+side. Still at the present time when a few of us old colleagues of
+Goschenen, Airolo or Altorf meet, it is not without emotion that we
+recall the old days, the joyful reunions at which he cheered the whole
+table with his broad and genial laugh.--_Maxime Helene, in La Nature._
+
+       *       *       *       *       *
+
+
+
+
+THE NEW HARBOR OF VERA CRUZ.
+
+
+Besides the enormous engineering work of rendering navigable one of the
+mouths of the Mississippi Delta, and the continuous labor of developing
+the more original and still bolder project for an Isthmian ship railway,
+Mr. James B. Eads has been engaged in the design of new and extensive
+harbor works at Vera Cruz, which, when completed, will secure for that
+city a commodious and secure port. The accompanying plan shows the
+natural features of the locality, as well as the new works. The harbor
+is formed by the coast line from the Punta de la Caleta to the Punta de
+Hornos, and by La Gallega reef. From the first named point a coral reef,
+nearly dry at low water, extends out about 300 yards into the gulf, and
+a similar one of about the same length runs out from the Punta de
+Hornos. Between these is a bay 2,000 meters wide, and at its northwest
+end lies the city of Vera Cruz. The bay is partly inclosed by an island
+or reef--La Gallega--which, on the harbor front, has a length of 1,200
+meters. Beyond this, and to the southeast, is another small island--the
+Lavendera reef. Between the end of this reef and that projecting from
+the Punta de Hornos is 320 meters wide. As will be seen from the plan
+the natural harbor is exposed to the gale from the north and northwest,
+while the formation affords general protection from the northeast and
+southeast thanks to five large coral reefs. Not unfrequently, however,
+heavy seas sweep through the wide channels between these small islands
+interfering seriously with vessels lying alongside the present limited
+wharfage. Northeast, La Gallega and Gallaguilla reefs run northward from
+the harbor for 3,300 meters and these with the main coast line, form a
+bay exposed to the full fury of the winds from the north, and when
+northern winds prevail rough water is driven through the passage between
+La Gallega and Caleta reefs with great violence, and sets up a rapid and
+dangerous current into the harbor.
+
+[Illustration: NEW HARBOR AT VERA CRUZ.]
+
+From the foregoing it will be seen that, while presenting some
+advantages, the natural harbor of Vera Cruz possesses many drawbacks and
+dangers which the design of Mr. Eads will completely remove. The leading
+features of the works about to be carried out are indicated on the plan.
+They comprise
+
+1. The construction of a sea wall between La Gallega and the Lavendera
+reefs, with an extension over the latter.
+
+2. The construction of a sea wall from Punta de la Caleta to La Gallega.
+This part of the work will be begun after the completion of the first
+wall to a height of at least 3 ft. above low water.
+
+3. A dike connecting the northern ends of the first two dikes with each
+other, and stretching across the southern part of La Gallega, to prevent
+the seas which sometimes break over this reef from entering the harbor.
+The wall between La Gallega and Lavendera will not only cut off the
+rough water during northerly gales, but will also effectually prevent
+the deposition of sand in the harbor, because the through passage to the
+northwest will be stopped. Passages closed by sluice gates will be
+formed through this wall at about low water level, so that at any time
+the harbor may be flushed out and stagnation prevented.
+
+4. After the construction of the inclosing walls the harbor will be
+dredged out and cleared of coral to a depth of 25 ft. below low water.
+
+5. Following these works of primary importance comes the construction of
+a wooden roadway from the Hornos reef to the northwestern dike. This
+roadway will form the south front of the harbor, and the excavated
+material will be deposited on the space between the roadway and the
+existing bottom, so as ultimately to make it a permanent work with a
+masonry retaining wall fronting the harbor. The land between the roadway
+and the city would also be reclaimed to the extent of more than 740,000
+square yards.
+
+6. The construction of wooden piers at right angles to the roadway,
+which would be extended to run around the harbor as trade required it,
+for ships to be alongside for loading and unloading. The construction of
+these short piers would be similar to those used in New York and other
+United States ports, and they might afterward be replaced by masonry if
+the increase in trade justified so large an expenditure.
+
+7. The erection of a lighthouse, at or near the eastern end of the
+Lavendera sea wall of a second on the eastern side of La Gallaguilla
+reef, and of another on the west side of La Blanquilla reef. These
+houses will be furnished with distinctive signals to enable steamers
+running in before another to run with safety between La Gallaguilla and
+La Blanquilla as soon as the Lavendera light is seen between the other
+two.
+
+The width of deep water at the entrance between the Lavendera and Hornos
+reefs will be 1,000 ft. The estimated cost of these extensive works is
+ten millions of dollars, a large sum for the Mexican Republic to expend
+in harbor improvements at one port but it will doubtless be found a
+profitable investment as it will tend greatly to promote trade, and so
+increase indefinitely the commerce of the port.
+
+Mr. Eads' plan having been approved by the Mexican Government the work
+was formally commenced on the 14th of last August. Plans were also
+furnished by him at the request of the Government, for deepening the
+mouth of the Panuco River upon which is located the city of Tampico, the
+Gulf terminus of the Mexican central railway system.--_Engineering._
+
+       *       *       *       *       *
+
+
+
+
+COST OF POWER TO MAKE FLOUR.
+
+
+The following estimate of the cost of the power required to manufacture
+a barrel of flour is taken from the _Miller_. The calculation would
+hardly hold good in this country owing to difference in cost of fuel
+attendance etc., but is nevertheless of interest.
+
+"The cost of a steam motor per 20 stone (280 lb.) sack of flour depends
+entirely on local circumstances. It depends first, on the amount of
+power expended in the production of a sack of flour, that is on its mode
+of manufacture, and it depends, secondly, on the cost of the necessary
+amount of power, that is, on the cost of fuel burned per horse power The
+average consumption of coal of first class steam engines may be taken at
+2 lb. per hour per indicated horse power.
+
+"Supposing a mill with six pairs of stones, two pairs of porcelain
+roller mills, and the necessary dressing, purifying, and wheat cleaning
+machinery to require a steam motor of 100 indicated horse power to drive
+it, then the average consumption of fuel in this mill would be 200 lb.
+of coal per hour. Such a mill working day and night will turn out about
+400 sacks of flour per week of, say, 130 hours, so that 200 X 13 =
+26,000 lb. of coal would be required to manufacture 400 sacks of flour.
+The cost of this quantity of coal may be taken at, say, £12 (about
+$58.32), and for cost of attending engine and boiler, cost of oil, etc.,
+another £3 (about $14.58) per week may be added; so that, in this case,
+the manufacture of 400 sacks of flour would cause an expenditure of £15
+($72.90) for the steam motor. Therefore the cost of the steam motor per
+20-stone sack of flour may be taken at 9d. (about 18 cents) per sack, if
+an improved low grinding system is used.
+
+"In this case it is supposed that about 55 per cent. of flour is
+obtained in the first run, leaving about 30 per cent. of middlings and
+about 12 per cent. of bran, which is finished in a bran duster. The
+middlings are purified, ground over one pair of middling stones, then
+dressed through a centrifugal and the tailings of the latter are passed
+over one of the porcelain roller mills, whereas the other porcelain
+roller mill treats the second quality of middlings coming from the
+purifier. The products from the two porcelain roller mills are dressed
+through a second centrifugal, and the whole flour is mixed into one
+straight grade. Four pairs of stones are supposed to work on wheat, one
+on middlings, and one pair is sharpening. The first run is supposed to
+be dressed through two long silk reels. Of course, not every steam motor
+has so low a consumption of coal as two pounds per hour per horse power;
+it often amounts to three, four, and five pounds per hour. In that case,
+of course, the cost of steam power per sack is much greater than 9d. per
+sack. A greater number of breaks does not necessarily increase the cost
+of steam power per sack of flour. Although more machines may be
+employed, each of them may require less horse power; so that the total
+amount of power required for manufacturing an equal amount of flour may
+not be greater in the case of gradual reduction.
+
+"As, however, the cost of maintenance may be slightly greater in the
+latter case, on account of a greater number of more elaborate machines,
+the cost of manufacturing a sack of flour may be a little greater when
+gradual reduction is employed, taking into account the total expenses of
+the mill and interest on the capital employed.
+
+"Water motors are generally a much cheaper source of energy than steam
+motors, but they are not so reliable and constant as the latter. The
+very irregular supply of water sometimes causes stoppages of the mill,
+and often a reserve steam engine has to be provided in order to assist
+the water motor when the quantity of water decreases during the summer
+months. Wind motors were formerly extensively used for milling purposes,
+but they are now gradually disappearing. They are too irregular and
+unreliable, although they utilize a very cheap motive power. It is not
+advantageous to expend a large amount of capital for a mill which often
+is unable to work at the very time when there are favorable
+opportunities for doing profitable business. Animal motors are too dear.
+They are only suitable for driving very small mills in out of the way
+localities."
+
+       *       *       *       *       *
+
+
+
+
+DRIVING GEAR MECHANISM FOR LIFT HAMMERS.
+
+
+A very interesting system of driving gear for lift hammers was applied
+in an apparatus exhibited at Frankfort in 1881 by Mr. Meier of Herzen.
+The arrangement of the mechanism is shown in Figs. 1 and 2. In the upper
+part of the hammer-frame there is a shaft which is possessed of a
+continuous rotary motion, and, with it, there is connected by a friction
+coupling a drum that receives the belt from which is suspended the
+hammer. In the apparatus exhibited, the mechanism is so arranged that
+the hammer must always follow the motion of the controlling lever in the
+same direction; but a system may likewise be adopted such that the
+hammer shall continue to operate automatically, when and so long as a
+lever prepared for such purpose is lowered.
+
+_ab_ is the shaft having a continuous rotary motion, and upon which are
+fixed the pulley, c, the fly-wheel, d, and the friction-disk, e.
+Upon one of the extremities of the driving shaft is fixed an elongated
+sleeve, formed of the drum, g, and of the screw, f, carried by the
+nut, h. This latter is supported in the frame in such a way that it
+cannot turn, but can move easily in the direction of the axis. Such
+motion may be produced by the spring, i, and its extent is such that
+the drum, g, is brought in contact with the friction-disk, e.
+
+The hand-lever, k, rod, l, and bent lever, m, serve to bring about
+a motion in the opposite direction, and which disengages the drum, g,
+from the disk, e, and lets the hammer fall; the drum being then able
+to turn freely. If the lever, k, be afterward raised again, the
+spring, i, will act anew and couple the drum with the driving-shaft,
+so that the hammer will be lifted. In this rotary motion the screw, f,
+turns or re-enters into its nut, which it displaces toward the left,
+since it cannot itself move in that direction until the rectilinear
+motion be wiped out, and the power of the spring be thus overcome. At
+the same moment, the screw should naturally also make this rectilinear
+movement forward, that is to say, the coupling would be disengaged, if,
+at the least lateral motion toward the right, the spring, i, did not
+push the system toward the left. There is thus produced a state of
+equilibrium such that there is just enough friction between the disk,
+e, and the drum, g, to keep the hammer at rest and suspended.
+Through the action of an external force which lowers the lever, K, the
+hammer at once falls, and the screw issues anew from its nut and brings
+the parts into their former positions.
+
+[Illustration: MEIER'S DRIVING GEAR MECHANISM FOR LIFT HAMMERS.]
+
+       *       *       *       *       *
+
+
+
+
+DE JUNKER & RUH'S MACHINE FOR CUTTING ANNULAR WHEELS.
+
+
+The machine shown in Figs. 1, 2, and 3 has been devised by Messrs.
+Junker & Ruh, of Carlsruhe, for cutting internally-toothed gear-wheels.
+The progress of the work is such that the wheel is pushed toward the
+tool by a piece, n, provided with a curve guide, and that the tool is
+raised and separated from the wheel after a tooth has been cut, in order
+to allow the wheel to revolve one division further.
+
+The tool is placed in a support, b, which is fixed to the upright,
+d, in such away that it may revolve; and this support is connected to
+the frame, a, of the machine. A strong flat spring, f, constantly
+presses the tool-carrier, b, toward the upright, d, as much as the
+screw, g, will permit; and this pressure and the tension of the belt
+draw the tool downward. The screws, g, determine the depth of the cut,
+and compensate for the differences in the diameter of the tool.
+
+[Illustration: MACHINE FOR CUTTING ANNULAR WHEELS.]
+
+The wheels to be cut are set by pressure into a wrought iron ring, with
+which they are placed in a sleeve or support, h. The connection
+between the two is assured by means of a nut, c. The axle of the
+support, h, is held in the upright of the carriage, k, which
+receives from a piece, l, placed on the driving-shaft, n, a slow
+forward motion toward the tool, and a rapid motion backward. The
+trajectory curve or groove of special form of the piece, l, in which
+moves the conducting roller, o, of the carriage, is not closed
+everywhere on the two sides, in that the guides that limit it extend
+only on the part strictly necessary. This arrangement permits of the
+roller being made to leave the trajectory in order that the carriage may
+be drawn back to a sufficient distance from the tool when the wheel is
+finished, so as to replace the latter by another.
+
+One hollow is cut during each forward travel of the carriage; and, when
+such travel is finished, a cam-disk, p, placed on the shaft, n,
+lifts the tool-carrier, b, and thus draws the cutting-tool out of the
+hollow cut by it, so that the carriage cam can then move back without
+restraint. In the interim, the sleeve, h, which supports the wheel,
+revolves one tooth through the following arrangement: On the axis, e,
+of this sleeve there are two ratchet-wheels, r and s, the number of
+whose teeth is equal to that of the teeth to be cut in the wheel. The
+wheel, r, produces the rotation of the sleeve, h, and the wheel,
+s, keeps the shaft stationary during the operation. The two wheels are
+set in motion by a lever, t, or by its click, this lever being raised
+at the desired moment on the free extremity of the driving shaft, n,
+by a wedge, u. The short arm of the lever, t, engages, through its
+point of appropriate shape, with the teeth of the wheel, s, so as to
+keep this latter stationary while the tool is cutting out the interspace
+between the teeth. When the lever, t, is raised, this point is at
+first disengaged from the wheel, s; and the raising of the lever being
+prolonged, the button, i, places itself against the upper curve of the
+slot in the lever, q, and raises that likewise. q is connected with
+the lever, v, which revolves about the axis, e, and v carries the
+click, w, so that when the lever, v, is raised, the wheel, r,
+turns forward by one tooth. When the lever, t, is lowered, as the
+wedge, u, turns more, its click holds the wheel, s, stationary. This
+series of operations is repeated until the last interspace between the
+teeth has been cut, when the machine stops automatically as follows: A
+cam of the disk, A, which receives from the shaft, n, through
+cone-wheels, a motion corresponding to that of the wheels, r and s,
+abuts against the two-armed lever, z, and this latter then disengages
+the rod, y, so that the weight, G, can move the fork, B, in such a way
+that the belt shall pass from the fast to the loose pulley.
+
+Motion is communicated to the machine as a whole by the shaft, C, which
+is provided with a fast and loose pulley. As shown in the engraving, the
+pulley, D, moves the tool, and the pulley, E, causes the revolution of
+the shaft, n, through a helicoidal gearing, F.
+
+The construction of the tool carrier is represented in detail in Fig. 3.
+The cutting tool, F, rests on a sleeve forming part of the pulley,
+r1, against which it is pressed by a nut, while its position is
+fixed by a key. The axle, s1, of the tool is held in two boxes, in
+which it is fixed by screws. In order that the tool may be placed
+exactly in the axis of the wheel to be toothed, and that also the play
+produced by lateral wear of the pulley, r1, may be compensated for,
+two screws, r2, are arranged on the sides. All rotation of the
+shaft, s1, is prevented by a screw, o, which traverses the cast
+iron stirrup, C, and the steel axle box.
+
+       *       *       *       *       *
+
+
+
+
+RECENT HYDRAULIC EXPERIMENTS.
+
+
+At a late meeting of the Institution of Civil Engineers, the paper read
+was on "Recent Hydraulic Experiments," by Major Allan Cunningham, R.E.
+
+This paper was mainly a general account of some extensive experiments on
+the flow of water in the Ganges Canal, lasting over four years--1874-79.
+Their principal object was to find a good mode of discharge measurements
+for large canals, and to test existing formulæ. There are about 50,000
+velocity, and 600 surface-slope measurements, besides many special
+experiments. The Ganges Canal, from its great size, from the variety of
+its branches abounding in long straight reaches, and from the power of
+control over the water in it, was eminently suited for such experiments.
+An important feature was the great range of conditions, and, therefore,
+also of results obtained. Thus the chief work was done at thirteen sites
+in brickwork and in earth, some being rectangular and others
+trapezoidal, and varying from 193 ft. to 13 ft. in breadth, and from 11
+ft. to 7 in. in depth, with surface-slopes from 480 to 24 per million,
+velocities from 7.7 ft. to 0.6 ft. per second, and discharges from 7,364
+to 114 cubic feet per second. For all systematic velocity measurements,
+floats were exclusively used, viz., surface floats, double floats, and
+loaded rods. Their advantages and disadvantages had been fully discussed
+in the detailed treatise "Roorkee Hydraulic Experiments"--1881. They
+measured only "forward velocity," the practically useful part of the
+actual velocity. The motion of water, even when tranquil to the eye, was
+found to be technically "unsteady;" it was inferred that there is no
+definite velocity at any point, and that the velocity varies everywhere
+largely, both in direction and in magnitude. The average of, say, fifty
+forward velocity measurements at any one point was pretty constant, so
+that there must be probably average steady motion. Hence average forward
+velocity measurements would be the only ones of much practical use. To
+obtain these would be tedious and costly, and special arrangements would
+be required to obviate the effects of a change in the state of water,
+which often occurred in a long experiment, as when velocities at many
+points were wanted.
+
+As to surface-slope its measurement--from nearly 600 trials--was found
+to be such a delicate operation that the result would be of doubtful
+utility. This would affect the application of all formulas into which it
+entered. The water surface was ascertained, on the average of its
+oscillations, to be sensibly level across, not convex, as supposed by
+some writers. There were 565 sets of vertical velocity measurements
+combined into forty-six series. The forty-six average curves were all
+very flat and convex down stream--except near an irregular bank--and
+were approximately parabolas with horizontal axes; the data determined
+the parameters only very roughly; the maximum velocity line was usually
+below the service, and sank in a rectangular channel, from the center
+outward down to about mid-depth near the banks. Its depression seemed
+not to depend on the depth, slope, velocity, or wind; probably the air
+itself, being a continuous source of surface retardation, would
+permanently depress the maximum velocity, while wind failed to effect
+this, owing to its short duration. On any vertical the mid-depth
+velocity was greater than the mean, and the bed velocity was the least.
+The details showed that the mid-depth velocity was nearly as variable
+from instant to instant as any other, instead of being nearly constant,
+as suggested by the Mississippi experimenters.
+
+The measurement of the mean velocity past a vertical was thought to be
+of fundamental importance. Loaded rods seemed by far the best for both
+accuracy and convenience in depths under 15 ft. They should be immersed
+only 0.94 of the full depth. The chief objection to their use,
+that--from not dipping into the slack water near the bed--they moved too
+quickly, was thus for the first time removed. A double float with two
+similar sub-floats at depths of 0.211 and 0.789 of the full depth would
+also give this mean with more accuracy and convenience than any
+instrument of its class; this instrument is new. Measurement of the
+velocity at five eighths depth would also afford a fair approximation.
+
+One hundred and fourteen average transverse velocity curves were
+prepared from 714 separate curves. These average curves were all very
+flat, and were convex down stream--over a level or concave bed--and
+nearly symmetric in a symmetric section. The velocity was greatest near
+the center, or deepest channel, decreased very slowly at first toward
+both banks, more rapidly with approach to the banks or with shallowing
+of the depth, very rapidly close to the banks, and was very small at the
+edges, possibly zero. The figure of the curve was found to be determined
+by the figure of the bed, a convexity in the bed producing a concavity
+in the curve and _vice versa_, and more markedly in shallow than in deep
+water. Curves on the same transversal, at the same site, and with
+similar conditions, but differing in general velocity, were nearly
+parallel projections. At the edges there was a strong transverse surface
+flow from the edge toward mid-channel, decreasing rapidly with distance
+from the edge. The discussion showed that it was almost hopeless to seek
+the geometric figure of the curves from mere experiment.
+
+Five hundred and eighty-one cubic discharges were measured under very
+varied conditions. The process adopted contained three steps: (1)
+Sounding along about fifteen float courses, scattered across the site in
+eight cross sections; time, say four hours. (2) Measurement of the mean
+velocities through the full depths in those float courses, each thrice
+repeated; time, say four hours. (3) Computation, say two hours. This
+process was direct and wholly experimental; each step was done in a time
+which gave some chance of a constant state of water. From an extended
+comparison of all results under similar conditions, it appeared that the
+above process yielded, under favorable circumstances, results not likely
+to differ more than 5 per cent. The sequel showed that in a channel with
+variable regimen, a discharge table for a given site must be of at least
+double entry, as dependent on the local gauge-reading, and on the
+velocity or surface-slope.
+
+Special attention was paid to rapid approximations to mean sectional
+velocity. The mean velocity past the central vertical, the central
+surface velocity, and Chézy's quasi-velocity--i.e.,
+
+  100 x Sqrt (R x S)
+
+where R = the hydraulic mean depth, and S = surface slope--were tried in
+detail; thus 100, 76, and 83 average values thereof respectively were
+taken from 581, 313, and 363 detail values. The ratios of these three
+velocities to the mean velocity were taken out, and compared in detail
+with Bazin's and Cutter's coefficients. Other formulæ were contrasted
+also in slight detail. Kutter's alone seemed to be of general
+applicability; when the surface slope measurement is good, and the
+rugosity coefficient known for the site--both doubtful matters--it would
+probably give results within 7½ per cent. of error. Improvement in
+formulæ could at present be obtained only by increased complexity, and
+the tentative research would be excessively laborious. Now the first two
+ratios varied far less than the third; thus their use would probably
+involve less error than the third, or approximation would be more likely
+from direct velocity measurement than from any use of surface slope. The
+connection between velocities was probably a closer one than between
+velocity and slope; the former being perhaps only a geometric, and the
+latter a physical one. The mean velocity past the central vertical was
+recommended for use, as not being affected by wind; the reduction
+coefficient could at present only be found by special experiment for
+each site. Three current meters were tried for some time with a special
+lift, contrived to grip the meter firmly parallel to the current axis,
+so as to register only forward velocity, and with a nearly rigid gearing
+wire. No useful general results were obtained. Ninety specimens of silt
+were collected, but no connection could be traced between silt and
+velocity; it seemed that the silt at any point varied greatly from
+instant to instant, and that the quantity depended not on the mean
+velocity, but probably on the silt in the supply water. Forty
+measurements of the evaporation from the canal surface were made in a
+floating pan, during twenty five months. The average daily evaporation
+was only about 1/10 in. The smallness of this result seemed to be due to
+the coldness of the water--only 63 deg. in May, with 165 deg. in the sun
+and 105 deg. in shade. Lastly, it must suffice to say that great care
+was taken to insure accuracy in both fieldwork and computation.
+
+       *       *       *       *       *
+
+
+
+
+THE GERM.
+
+By ARTHUR ATKINS.
+
+
+There seems to have sprung up within a few mouths a tendency to revive
+the discussion on that hackneyed question, "Shall the germ be retained
+in the flour?" This question has been more than once answered in the
+negative by both scientific and practical men, but recently certain
+prominent persons have come to the conclusion that every one has been
+wrong on this point, and the miller should by all means retain the germ.
+Now the nutritive value of the germ cannot be disputed, but there are
+two circumstances which condemn it us an ingredient of flour. The first
+is that the albuminoids which it contains are largely soluble, and this
+means that good light bread from germy flour is impossible. I have not
+time to go into a detailed explanation of the chemical reasons for this,
+but they may be found in a series of articles which appeared in _The
+Milling World_ about a year ago. In the next place, the oil contained in
+the germ not only discolors the flour, but seriously interferes with its
+keeping qualities. Now color is only a matter of taste, and if that were
+the only objection to the germ, it might be admitted, but we certainly
+do not want anything in our flour to interfere with making light, sweet
+bread, and will render it more liable to spoil. If our scientists can
+discover some method of obviating these objections, it will then be time
+enough to talk about retaining the germ. Meanwhile millers know that
+germy flour is low priced flour, and they are not very likely to reduce
+their profits by retaining the germ.--_Milling World._
+
+       *       *       *       *       *
+
+
+
+
+WHEAT TESTS.
+
+
+There was considerable complaint last season, on the part of wheat
+raisers in sections tributary to Minneapolis, on account of the rigid
+standard of grading adopted by the millers of that city. It was asserted
+that the differentiation of prices between the grades was unjustly great
+and out of proportion to the actual difference of value. In order to
+ascertain whether this was the case or not, the Farmers' Association of
+Blue Earth County, Minn., decided to have samples of each grade analyzed
+by a competent chemist in order to determine their relative value.
+Accordingly specimens were secured, certified to by the agent of the
+Millers' Association of Minneapolis, and sent to the University of
+Minnesota for analysis. The analysis was conducted by Prof. Wm. A.
+Noyes, Ph.D., an experienced chemist, who has recently reported as
+follows:
+
+"The analyses of wheat given below were undertaken for the purpose of
+determining whether the millers' grades of wheat correspond to an actual
+difference in the chemical character of the wheat. For this purpose
+samples of wheat were secured, which were inspected and certified to by
+M. W. Trexa on April 13th of this year. The inspection cards contained
+no statement except the grade of the wheat and the weight per bushel,
+but the samples were all of Fife, for the purpose of a better
+comparison. The analyses of the wheat were made during October in this
+laboratory. In each case the wheat was carefully separated from any
+foreign substances before analysis. The results of analysis were as
+follows:
+
+                                        Grade     Grade       Grade
+                                        No. 1.    No. 2.      No. 3.
+  Weight per bushel..................   59 lb.    56½ lb.     55 lb.
+  Grains to weigh 10 grains..........    366       474         491
+                                        Per ct.   Per ct.     Per ct.
+  Foreign matter (seeds, etc.).......    0.41      0.20        1.57
+  Nitrogen...........................    2.09      2.08        2.17
+  Phosphorus.........................    0.35      0.46        0.46
+  Water..............................   12.34     11.31       11.85
+  Ash................................    1.59      1.92        1.97
+  Albuminoids (nitrogen multiplied
+    by 6¼)...........................   13.06     13.00       13.56
+  Cellulose..........................    2.03      2.37        2.50
+  Starch, sugar, fat, etc............   70.98     71.40       70.12
+
+"The analyses require but little comment. The only substances in which
+there is evident connection between the results of analysis and the
+grades of wheat are the cellulose, ash, and phosphorus. As regards the
+last substance, grades two and three seem to have the greatest food
+value. But it seems quite probable from the results that greater
+difference would be found between different varieties of wheat of the
+same kind than is shown here between different grades of the same
+variety of wheat. However, it does not necessarily follow from this that
+the different grades of wheat are of nearly equal value to the miller
+for the purpose of making flour. That is a question which can be best
+answered by determining accurately the amount and character of the flour
+which can be made from each grade of wheat. If possible, the
+investigation will be continued in that direction."
+
+As Prof. Noyes justly remarks, the value of the different grades of
+wheat can best be determined by a comparison of the results of reducing
+them to flour, but an intelligent study of the table given above would
+of itself be sufficient to indicate the justness of the grading. In the
+first place, even were the percentages of the different components
+exactly the same in each grade, still the difference in weight would of
+itself be sufficient to justify a marked difference in price. This
+requires no proof, for, other things being equal, fifty-nine pounds is
+worth more than fifty-five pounds. Again, the figures show that No. 3
+contained nearly four times as much foreign matter as No. 1. Millers
+certainly should not be expected to pay for foreign seeds or other
+substances valueless for their purpose, at the price of wheat. Finally,
+if the analysis proves anything, it proves that the lower grades contain
+a decidedly larger percentage of components which it is generally
+agreed, whether directly or the reverse, ought not to be incorporated
+with the flour, and are, therefore, of comparatively little value to the
+miller. This is shown by the relative amounts of cellulose, ash, and
+phosphorus present. Cellulose, as every one knows, is the woody,
+indigestible substance which is found in the bran, and the greater the
+amount of cellulose, the heavier will be the bran in proportion to the
+flour producing elements. According to the figures presented, No. 3
+contained nearly one-quarter more cellulose than No. 1, while the amount
+in No. 2 was slightly less than in No. 3. The ash, too, which represents
+the mineral constituents of the wheat, is directly dependent upon the
+quantity of bran. Here, too, the lowest grade is shown to yield about
+one-quarter more than the highest. The larger percentage of phosphorus
+in the lower grades is suggested by the analyst to indicate their
+greater food value in this respect. So it would, were we in the habit of
+boiling our wheat and heating it whole, or of using "whole wheat meal."
+But, fortunately or unfortunately, the bread reformers have not yet
+succeeded in inoculating any considerable portion of the community with
+their doctrines, and hence the actual food value of any sample of wheat
+must be ascertained, not directly from the composition of the wheat, but
+from the composition of the flour made therefrom. Now, as already
+stated, phosphorus, like the other mineral components, is found almost
+entirely in the bran. Its presence in greater quantity, therefore,
+simply adds to the testimony that a larger proportion of the low grade
+wheat must be rejected than of the higher grade. It should be evident to
+the complaining farmers that the millers were in the right of the
+question, on this occasion at least.
+
+It is expected that further analysis will be made, this time of the
+flour made from the different grades of wheat. If these investigations
+be properly conducted, we have no doubt that they will simply confirm
+the evidence of the wheat tests. A chemical analysis alone, however,
+will not be sufficient. The quantity of flour obtained from a given
+amount of wheat must also be ascertained and its quality further tested
+by means best known to millers, as regards "doughing-up," keeping
+qualities, color, etc. And then the result can be no less than to show
+what millers already knew--that the best quality of flour, commanding
+the top prices in the market, cannot be obtained from an inferior
+quality of wheat.--_Milling World._
+
+       *       *       *       *       *
+
+
+
+
+APPARATUS FOR PRINTING BY THE BLUE PROCESS.[1]
+
+    [Footnote 1: Read June 21, 1882, before the Boston Society of
+    Civil Engineers.]
+
+By CHANNING WHITAKER.
+
+
+The blue process is well known to the members of the society, and I need
+not take time to describe it; but with the ordinary blue process
+printing frame the results are sometimes unsatisfactory, and now that
+the process has come to be so commonly used I have thought that an
+account of an inexpensive but efficient printing frame would be of
+interest. The essential parts of the apparatus are its frame, its glass,
+its pad or cushion, its clamps, and the mechanism by which the surface
+of the glass can easily be made to take a position that is square with
+the direction of the sun's rays.
+
+_The Blue Process Printing Frame in Common Use.--Its Defects._--The pad
+of the apparatus in common use consists of several thicknesses of
+blanketing stretched upon a back board. The sensitized paper and the
+negative are placed between the pad and the plate glass, and the whole
+is squeezed together by pressure applied at the periphery of the glass
+and of the back-board. Both the glass and the back-board spring under
+the pressure, and it results that the sensitized paper is not so
+severely pressed against the negative near the center of the glass as it
+is near the edges. If at any point the sensitized paper is not pressed
+hard up against the negative, a bluish tinge will appear where a white
+line or surface was expected. With an efficient printing frame and
+suitable negatives, these blue lines will never appear, and it was to
+prevent the production of defective work that I undertook to improve the
+pad of the printing frame.
+
+_The Printing Frame Used in Ordinary Photography._--Very naturally, I
+first examined the printing frame used in ordinary photography. This
+frame is extremely simple, and is very well adapted to its use. It is,
+undoubtedly, the best frame for blue process printing, when the area of
+the glass is not too large. The glass is set in an ordinary wooden
+frame, while the back-board is stiff and divided into two parts. A flat,
+bow-shaped spring is attached by a pivot to the center of each half of
+the back-board. The two halves of the back-board are hinged together by
+ordinary butts. Four lugs are fastened to the back of the frame, and,
+when the back-board is placed in position, the springs may be swung
+around, parallel to the line of the hinges, and pressed under the lugs,
+so that the back of the back-board is pressed most severely at the
+center of each half, while the glass is prevented from springing away
+from the back-board by the resistance of the frame at its edges. Unless
+the frame is remarkably stiff, it will resist the springing of the glass
+more perfectly in the neighborhood of the lugs than elsewhere. It will
+now be seen that, on account of the manner in which the pressure is
+applied, the back-board tends to become convex toward the glass, while
+the adjacent surface of the glass tends to become concave toward the
+back-board; and that with such a frame, the pressure upon all parts of
+the sensitized paper is more nearly uniform than when the pressure is
+applied in the manner before described. With a small frame of this
+description, a piece of ordinary cotton flannel is used between the
+back-board and the sensitized paper, and, with larger sizes, one or more
+thicknesses of elastic woolen blanket are substituted for the cotton
+flannel. There is an advantage in having a hinged back-board like that
+which has been described, because, when the operator thinks that the
+exposure to sunlight has been sufficiently prolonged, he can turn down
+either half of the back and examine the sensitized paper, to see if the
+process has been carried far enough. If it has not, the back-board can
+be replaced, and the exposure continued, without any displacement of the
+sensitized paper with respect to the negative. This is an important
+advantage.
+
+_An Efficient Blue Process Frame, for Printing from Large Negatives, or
+for Printing Simultaneously from many Small Ones._--In order to be
+efficient, such a frame must be capable of keeping the sensitized paper
+_everywhere tightly pressed against the negative_. Again, such a frame,
+being large, is necessarily somewhat heavy. It should be so mounted that
+it can be handled with ease; and, in order that it may print quickly, it
+should be so arranged that it can be turned without delay, at any time,
+into a position that is square with the direction of the sun's rays.
+
+Undoubtedly, if a sufficiently thick plate of glass should be used, the
+ordinary photographic printing frames would answer the purpose, whatever
+the size, but very thick plate glass is both heavy and expensive.
+Commercial plate glass varies in thickness from one-fourth to three
+eighths of an inch, and the thicker plates are rather rare. A large
+plate of it is easily broken by a slight uniformly distributed pressure.
+But the pressure that is required for the blue process printing,
+although slight, is much greater than is used in the ordinary
+photographic process. For the sensitized paper that is used in the blue
+process printing is, comparatively, very thick and stiff, and it may
+cockle more or less, while the paper that is used in ordinary
+photography is thin and does not cockle. Now, it is easy to see that a
+pressure severe enough to flatten all cockles must be had at every part
+of the sensitized paper, and that, if the comparatively thin,
+inexpensive, light weight, commercial plate glass is to be used, it is
+desirable to have the pressure _nowhere much greater than is needed for
+that purpose_, lest the fragile glass should be fractured by it. In each
+of my large frames I use the commercial plate glass; instead of the
+cushion of cotton flannel, or of flannel, I use a cushion filled with
+air of sufficiently high pressure to flatten all cockles, and to press
+all parts of the sensitized paper closely against the negative; and
+instead of the hinged back-board I use a back-board made in one piece
+and clamped to the frame of the glass at its edges. Connected with the
+cushion is a pressure gauge, and a tube with a cock, for charging the
+cushion with air from the lungs. Experience shows what pressure is
+necessary with any given paper, and the gauge enables one to know that
+the pressure is neither deficient nor in excess of that which is safe
+for the glass.
+
+[Illustration: PLAN. COTTON FLANNEL REMOVED.]
+
+[Illustration: SECTION AT CO.]
+
+_The Construction of the Air-Cushion._--The expense of such an
+air-cushion seemed at first likely to prevent its being used; but a
+method of construction suggested itself, the expense of which proved to
+be very slight. The wooden back-board, as constructed, is made in one
+piece containing no wide cracks. It has laid upon it some thick brown
+Manila paper, the upper surface of which has been previously shellacked
+to make it entirely air-tight. Upon this shellacked surface is laid a
+single thickness of thin paper of any kind; even newspaper will answer.
+Its object is simply to prevent the sheet rubber, which forms the top of
+the air-cushion, from sticking to the shellacked paper. The heat of the
+sun is often sufficient to bring the shellac to a sticky state. It would
+probably answer as well to shellac the under side of the paper, and to
+use but one sheet, but I have not tried this plan. Around the periphery
+of the pad, there is laid a piece of rubber gasket about one and a half
+inches wide, and about one-eighth of an inch thick. In order that the
+gasket may not be too expensive, it is cut from two strips about three
+inches wide. One of them is as long as the outside length of the frame,
+and the other is as long as the outside width of the frame. Each of
+these strips is cut into two L-shaped pieces, an inch and a half in
+width, with the shorter leg of each L three inches long. When the four
+pieces are put together a scarf joint is made near each corner, having
+an inch and one-half lap. It is somewhat difficult to cut such a scarf
+joint as perfectly as one would wish, and it is best to use rubber
+cement at the joints. Over the gasket is laid a sheet of the thinnest
+grade of what is called pure rubber or elastic gum. Above this, and over
+the gasket, is placed a single thickness of cotton cloth, of the same
+dimensions as the gasket, and yet above this are strips of ordinary
+strap iron, an inch and a half wide and nearly one eighth of an inch
+thick. These strips are filed square at the ends and butt against each
+other at right angles. As the edges of the strips are slightly rounded,
+they are filed away sufficiently to form good joints wherever the others
+butt against them. The whole combination is bound together by ordinary
+stove bolts, one quarter of an inch in diameter, placed near the center
+of the width of the iron strips, and at a distance apart of about two
+and one-half inches. Their heads are countersunk into the strap iron. In
+making the holes for the stove bolts through the thin rubber, care
+should be taken to make them sufficiently large to enable the bolt to
+pass through without touching the rubber, otherwise the rubber may cling
+to the bolts, and if they are turned in their holes the rubber may be
+torn near the bolts and made to leak. A rough washer, under each nut,
+prevents it from cutting into the back-board. For the purpose of
+introducing air to, or removing air from, the pad, a three-eighths of an
+inch lock nut nipple is introduced through the back-board, the
+shellacked paper, and its thin paper covering. Without the back-board a
+T connects with the nipple. One of its branches leads, by a rubber tube,
+to the pressure gauge, which is a U-tube of glass containing mercury.
+The other branch has upon it an ordinary plug cock, and, beyond this, a
+rubber tube terminating in a glass mouth-piece. When it is desired to
+inflate the air-cushion, it is only necessary to blow into the
+mouth-piece. A pressure of one inch of mercury is sufficient for any
+work that I have yet undertaken. With particularly good paper, a lower
+pressure is sufficient. Upon the top of the pad is laid a piece of
+common cotton flannel with the nap outward, and with its edges tacked
+along the under edge of the back-board. The cotton flannel is not drawn
+tight across the top of the pad. The reason for employing a cotton
+flannel covering is this: When the sheet rubber has been exposed for a
+few days to the strong sunlight, it loses its strength and becomes
+worthless. The cotton flannel is a protection against the destruction of
+the rubber by the sunlight. I first observed this destruction while
+experimenting with a cheap and convenient form of gauge. I used, as an
+inexpensive gauge, an ordinary toy balloon, and I could tell, with
+sufficient accuracy, how much pressure I had applied, by the swelling of
+the balloon. This balloon ruptured from some unknown cause, and I made a
+substitute for it out of a round sheet of thin flat rubber, gathered all
+around the circumference. I made holes about one-quarter of an inch
+apart, and passing a string in and out drew it tight upon the outside of
+a piece of three eighths of an inch pipe, I then wound a string tightly
+over the rubber, on the pipe, and found the whole to be air-tight. This
+served me for some time, but one day, on applying the pressure, I found
+a hole in the balloon which looked as if it had been cut with a very
+sharp knife. That it had been so cut was not to be imagined, and on
+further examination I found that the fracture had occured at a line
+which separated a surface in the strong sunlight from a surface in the
+shade, at a fold in the rubber. I saw that all of the rubber which had
+been continuously exposed to the intense sunlight had changed color and
+had become whiter than before, and that that portion of the balloon had
+lost its strength. I then returned to the use of the mercury gauge, and
+took the precaution to cover my pad with cotton flannel, as a protection
+from the light and from other sources of destruction. This pad is upon
+the roof of the Institute; and is exposed to all weathers. As a
+protection from the rain and the snow, the whole is covered again with a
+rubber blanket. It has withstood the exposure perfectly well for a year,
+without injury. The gauge, made from flat rubber, is altogether so cheap
+and so convenient that I am now experimenting with one of this
+description having a black cloth covering upon the outside. The balloon
+is of spherical shape, the black cloth covering is of cylindrical shape,
+and I hope that this device will serve every necessary purpose. A
+sectional view of the air-cushion is offered as a part of this
+communication.
+
+_The Frame, which Contains the Plate Glass_, is made of thick board or
+plank, with the broad side of the board at right angles to the surface
+of the glass. A rabbet is made for the reception of the glass, and four
+strips of strap iron, overlapping both the glass, and the wood, and
+screwed to the wood, keep the glass in position. Strips of rubber are
+interposed between the glass and the wood and between the glass and the
+iron. The frame is hinged to the back-board by separable hinges, so that
+the glass can be unhinged from the pad without removing the screws.
+Hooks, such as are used for foundry flasks, connect the frame with the
+pad upon the opposite side. A frame made in this manner is very stiff
+and springs but little, and its depth serves an excellent purpose. The
+air-cushion and the frame are so mounted that they can be easily turned
+to make the surface of the glass square with the direction of the sun's
+rays. It is necessary to have a tell tale connected with the apparatus,
+which will show when the surface of the glass has been thus adjusted.
+The shadow of the deep frame is an inexpensive tell-tale, and enables
+the operator to know when the adjustment is right. I have now described,
+in detail, the construction of the air-cushion with its back-board, as
+well as that of the frame which holds the plate glass, and I think it
+will be evident that the first cost of the materials of which they are
+made is comparatively little, and that the workmanship required to
+produce it is reduced to a minimum. It will also, I think, be evident
+that a uniform pressure, of any desired intensity, can be had all over
+the surface of the sensitized paper for the purpose of securing perfect
+contact between it and the negative. The blue copies that are taken with
+this apparatus are entirely free from blue lines when the negatives,
+chemicals, and paper are good.
+
+_The Mechanism for Adjusting the Surface of the Glass, until it shall be
+Perpendicular to the Direction of the Sun's Rays._--I have found many
+uses for the blue copying process in connection with the work of
+instruction at the Massachusetts Institute of Technology. Notes printed
+by it are far better and less costly than those printed by papyrograph.
+I will not detain you now with an account of the uses that I have made
+of it. I will merely say that more than a year ago I found that my
+frame, which has a glass 3 feet x 4 feet, was wholly inadequate to the
+work in hand, and I tried to increase the production from it by
+diminishing the time of printing. The glass of this frame was
+horizontal, except when one of its ends was tilted off from the slides
+which guided it when pushed out of the window; and I knew that it took
+three or four times as long to print when the sun was low as it did when
+the sun was near the meridian. I made plans for mounting this frame upon
+a single axis, about which it could be turned after it had been pushed
+through the window, but I saw that no movement about a single axis would
+give a satisfactory adjustment for all times of the year, and I
+considered what arrangement of two axes would permit a rapid and perfect
+adjustment, at all times, with the least trouble to the operator. It was
+evident that when the sun was in the equatorial plane, the surface of
+the glass should contain a line which was parallel to the axis of the
+earth; and further, that if such a glass was firmly attached to an axis
+which was parallel to that of the earth, it would fulfill the desired
+purpose. For the glass, being once in adjustment, is only thrown out of
+position by the rotation of the earth, and if the glass is rotated
+sufficiently about its own axis, in a direction opposite to that of the
+earth, it will retain its adjustment. In order to have the adjustment
+equally good when the sun was either north or south of the equatorial
+plane, it was sufficient to mount a secondary axis upon the primary one
+and at right angles to it. About this the glass could be turned through
+an angle of 23½°, either way, from the position which it should have
+when the sun was in the equatorial plane.
+
+[Illustration: BLUE PROCESS PRINTING APPARATUS.]
+
+_The Construction of the Adjusting Mechanism._--I desired to have the
+mechanism as compact and inexpensive as possible, and to have the frame
+well balanced about the primary axis, in every position. I also desired
+to have a rotation of nearly 180° about the principal axis. The plan
+adopted will be most easily understood by referring to the drawing which
+illustrates it. The axes are composed chiefly of wood. They are built up
+from strips which are 3 inches × 7/8 inch, and from small pieces of 2
+inch plank. They are stiffly braced. A pair of ordinary hinges permit
+the secondary rotation to occur, while a pair of cast iron dowel pins
+with their sockets, such as are used in foundry flasks, serve as pivots
+during the primary rotation.
+
+_The Adjustments._--The adjustment about the secondary axis does not
+need to be made more frequently than once a week, or once a fortnight.
+In order to prevent rotation about this axis when in adjustment, two
+cords lead from points which are beneath the back board, and as far
+removed from the secondary axis as is convenient. Each cord passes
+forward and backward through four parallel holes in a wooden block which
+is attached to the primary axis. The cords can be easily slipped in the
+holes by pulling their loops, but the friction is so great that they
+cannot be slipped by pulling at either end. It takes about twice as long
+to make the adjustment as would be necessary if a more expensive device
+had been used; but this device is at once so cheap, so secure, and has
+so seldom to be used, that it was thought to be best adapted for the
+purpose. To prevent rotation from occurring about the primary axis when
+it is not desired, a bar parallel to the secondary axis is attached by
+its middle point to the primary axis near one end. A cord passes from
+either end of this bar through cam shaped clamps, which were originally
+designed for clamping the cords of curtains with spring fixtures. These
+clamps are cheap. They are easily and quickly adjusted, and are very
+secure.
+
+The whole apparatus can be located upon the roof of a building, or, if
+convenient, it can be mounted upon slides, and pushed through an open
+window when it is to be exposed to the light. If it is to be used upon a
+roof, a small hut, or shelter of some sort, near by is a great
+convenience to the operator, particularly in winter.
+
+_An Inexpensive Drying Case for Use in Coating the Paper._--When the
+apparatus is in continuous use, time may be saved by having a convenient
+arrangement for drying the sheets that have been coated with the
+sensitizing liquid. I have made an inexpensive drying case which serves
+the purpose very well. It consists simply of a light-tight rectangular
+case of drawers. There are twenty-five drawers in all. They are
+constructed in an inexpensive manner, and are the only parts of the case
+that are worth describing. They are very shallow, being but 1-7/8 inches
+deep, and as it appeared that the principal expense would be for the
+materials of which the bottoms of the drawers should be composed, it was
+decided to make the bottoms of cotton cloth. This cloth is stretched
+upon a frame, the dimensions of which are greater than that of the paper
+to be dried. The stock of which the frame is made is pine, 1¼ inches
+wide, and three-eighths of an inch thick. The corners are simply mitered
+together and attached to each other by means of the wire staples that
+are commonly used for fastening together pages of manuscript, and which
+are called "novelty staples." Eight staples are used at each miter, four
+above and four below the joint. Two of the staples, at the top and near
+the ends of the joint, are set square across it, and two others, at the
+top and near the middle of the joint, are placed diagonally across it.
+The staples at the bottom are similarly placed. The joint is quite firm
+and strong, and is likely to hold for an indefinite period with fair
+usage. The cloth, stretched upon the frame, is fastened to it by means
+of similar staples. A dark colored cloth not transparent to light is to
+be preferred. A strip of pine, 1-13/16 inches wide, and three eighths of
+an inch thick, forms the vertical front of the drawer, and prevents the
+admission of much light from the front while the sheet is drying. Two
+triangular knee pieces, three-quarters of an inch thick, serve to
+connect the front board with the frame, and four small screws with a few
+brads are used in attaching them. The lower edge of the front board
+drops one-quarter of an inch below the bottom of the drawer. My case
+stands in a poorly lighted room, and paper dried in this case and
+removed to a portfolio as soon as it is dry does not seem to be injured
+by the light that reaches it. With the case in a well lighted room, I
+should prefer to have outer doors to the case, made of ordinary board
+six or eight inches wide, hinged to one end, and arranged to swing
+horizontally across the front of the case. These would more completely
+prevent the admission of light. The opening of any one of the doors
+would allow three or four of the drawers to be filled, while the rest of
+the case would be comparatively dark at the same time.[2]
+
+    [Footnote 2: Since this paper was read, I have seen in the
+    office of the City Engineer of Boston a drying case which is
+    similar in some respects to the one that I have devised. It has
+    been longer in use than my own. The drawers are simply the
+    ordinary mosquito netting frames covered with cotton netting.
+    They have no fronts, but a door covers the front of the case,
+    and shuts out the light.]
+
+_The Portfolio for Protecting the Sensitized Paper from Exposure to
+Light._--The sensitized paper is very well protected from exposure to
+light, if kept in a portfolio or book, the brown paper leaves of which
+are considerably larger than the sensitized sheets. The sheets may be
+returned to such a book after exposure, and washed at the convenience of
+the operator. They can be washed more quickly and perfectly if _two_
+water-tanks are provided in which to wash them. A few minutes' soaking
+will remove nearly all of the sensitizing preparation which has not been
+fixed by the exposure. If the soaking is too long continued in water
+that is much discolored by the sensitizing preparation, the sheets
+become saturated with the diluted preparation, and they may become
+slightly colored by _after_ exposure. If the first soaking is not too
+long continued, and if the sheets are transferred at once to a second
+bath of clean water, which is kept slowly changing from an open faucet,
+they may remain there until the soluble chemicals have been entirely
+extracted, and there will be no risk of staining by after exposure.
+Washing in two tanks is of more consequence when the ground is white and
+the lines blue, than when the ground is blue and the lines white.
+
+_The Grades of Paper that are well Adapted for Blue Process Work._--I
+have tested many grades of paper, to ascertain if they were well adapted
+for blue process work. Some grades of brown Manila are very good; others
+have little specks embedded in their surfaces which refuse to take on a
+blue tint; still others, when printed upon, have white lines that are
+wider than the corresponding black lines of the negative. The blue
+obtained upon bond paper appears to be particularly rich, and the whites
+remain pure; but bond paper cockles badly, and the cockles remain in the
+finished print. Weston's linen record is an excellent paper. It is
+strong, cockles but little, and dries very smooth. A paper that is used
+by Allen & Rowell, for carbon printing, is comparatively cheap, and is
+an excellent paper. It is not so stiff as the linen record, and the
+whites are quite as pure. It does not cockle, neither does it curl while
+being sensitized. It comes in one hundred pound rolls, and is about
+thirty inches wide. The best papers are those that are prepared for
+photographic work. The plain Saxe and the plain Rives both give
+excellent results. Blue lines on a pure white ground can be obtained on
+these papers, from photographic negatives, without difficulty. None of
+the hard papers of good grade require the use of gum in the sensitizing
+liquid. The liquid penetrates the more porous papers too far when gum is
+not used, and without it good whites are seldom obtained upon porous
+paper.
+
+_The Best Chemicals for this Work_ are the _recrystallized_ red
+prussiate of potash and the citrate of iron and ammonia, _which is
+manufactured by Powers & Wightman_, of Philadelphia. If the red
+prussiate has not been recrystallized, the whites will be unsatisfactory
+and the samples of citrates of iron and ammonia which have come to us
+from other chemists than those named, have all proved unreliable for
+this process.
+
+_The Sensitizing Liquid.--Its Proportions._--The blue process was
+originally introduced from France, by the late Mr. A. L. Holley. I was
+indebted to Mr. P. Barnes, who was with Mr. Holley at the time, for an
+early account of it, and I had the first blue process machine that was
+in use in New England. Since 1876, instruction in the use of the blue
+process has been given to the students of mechanical engineering of the
+Massachusetts Institute of Technology, and they have caused its
+introduction into many draughting offices. The proportions of the
+sensitizing liquid, as originally given me by Mr Barnes, were as
+follows:
+
+  Red prussiate of potash............. 8 parts.
+  Citrate of iron and ammonia......... 8 parts.
+  Gum arabic.......................... 1 part.
+  Water.............................. 80 parts.
+
+_Results of Experiments._--In our use, it first appeared that the gum
+might be omitted from the preparation when sufficiently hard papers were
+used. Next, that a preparation containing
+
+  Red prussiate of potash........ 2 parts,
+  Citrate of iron and ammonia.... 3 "
+  Water......................... 20 "
+
+printed more rapidly. This preparation I continue to use when much time
+may elapse between sensitizing and printing; but, when the paper is to
+be printed immediately after sensitizing, I use a larger proportion of
+citrate of iron and ammonia. Before arriving at the conclusion that
+these proportions were the best to be used, I made a series of purely
+empirical experiments, beginning with the proportions:
+
+  Red prussiate of potash.......... 10 parts.
+  Citrate of iron and ammonia....... 1 part.
+  Water............................ 50 parts.
+
+and ending with the proportions:
+
+  Red prussiate of potash............... 1 part.
+  Citrate of iron and ammonia.......... 10 parts.
+  Water................................ 50 "
+
+I found the best plan for conducting these experiments to be: To coat a
+sheet of the paper with a given mixture; to cut the sheet into strips
+before exposure; to expose all the strips of the sheet, at the same
+time, to the direct sunlight without an intervening negative; and to
+withdraw them, one after another, at stated intervals. I found that with
+each mixture there was a time of exposure which would produce the
+deepest blue, that with over-exposure the blue gradually turned gray,
+and that if a curve should be plotted, the abscissas of which should
+represent the time of exposure, and the ordinates of which should
+represent the intensity of the blue the curves drawn would have
+approximately an elliptical form, so that if one knew the exact time of
+exposure which would give the best result with any mixture, one might
+deviate two or three minutes either way from that time without producing
+a noticeable result. I have found that, with the same paper, the same
+blue results with any good proportions of the chemicals named, provided
+a sufficient weight of both chemicals is applied to the surface; that an
+excess of the red prussiate of potash renders the preparation less
+sensitive to light, and very much lengthens the necessary time of
+exposure; that the prints are finer with some excess of the red
+prussiate; that an excess of the citrate of iron and ammonia hastens the
+time of printing materially; that a greater excess of the citrate causes
+the whites to become badly stained by the iron, while a still greater
+excess of the citrate, in a concentrated solution causes the sensitized
+paper to change without exposure to light, and to produce a redder blue
+or purple, which does not adhere to the paper, but may be washed off
+with a sponge. I have found that the cheapest method of reproducing
+inked drawings that have been made on thick paper is not to trace them,
+but to print the blues from a photographic glass negative; and also,
+that the dry plate process is well adapted to such work in offices, when
+one has become sufficiently experienced. Printed matter can also most
+easily and inexpensively be reproduced by the same means, when a small
+issue is required on each successive year. For the reproduction of
+manuscript by the blue process, the best plan that I have found has been
+to write the manuscript upon the thinnest blue tinted French note-paper,
+with black opaque ink--the stylographic ink is very good--and,
+afterward, to dip the paper into melted paraffine, and to dry the paper
+at the melting temperature. This operation, if cheaply done, requires
+special apparatus. For positive printing from the glass negative, I use
+a multiple frame, by the aid of which I can print from 16 negatives at
+the same time, upon a single sheet of paper. This frame is
+interchangeable with the one that contains the plate glass. The
+negatives are so arranged in the frame that the sheets can be cut and
+bound, as in the ordinary process of book binding. The time required for
+exposure, when printing from glass negatives, varies with the negative;
+and, in order to secure satisfactory results with the multiple frame it
+is necessary to stop the exposure of some, while the exposure of others
+is continued. I insert wooden or cloth stoppers into the frame for the
+purpose of stopping the exposure of certain negatives. When paraffined
+manuscript is to be printed from, I find it convenient to have it
+written on sheets of small size, and to have these mounted upon an
+opaque frame of brown Manila paper, printing sixteen or more at a time,
+depending upon the size of the printing frame. Many small tracings may
+be similarly mounted upon a brown paper multiple frame, and may be
+printed together upon a single sheet.
+
+       *       *       *       *       *
+
+
+
+
+SPECTRUM GRATINGS.
+
+
+At a recent meeting of the London Physical Society, Prof. Rowland, of
+Baltimore, exhibited a number of his new concave gratings for giving a
+diffraction spectrum. He explained the theory of their action. Gratings
+can be ruled on any surface, if the lines are at a proper distance apart
+and of the proper form. The best surface, however, is a cylindrical or
+spherical one. The gratings are solid slabs of polished speculum metal
+ruled with lines equidistant by a special machine of Prof. Rowland's
+invention. An account of this machine will be published shortly. The
+number of lines per inch varied in the specimens shown from 5,000 to
+42,000, but higher numbers can be engraved by the cutting diamond. The
+author has designed an ingenious mechanical arrangement for keeping the
+photographic plates in focus. In this way photographs of great
+distinctness can be obtained. Prof. Rowland exhibited some 10 inches
+long, which showed the E line doubled, and the large B group very
+clearly. Lines are divided by this method which have never been divided
+before, and the work of photographing takes a mere fraction of the time
+formerly required. A photographic plate sensitive throughout its length
+is got by means of a mixture of eosene, iodized collodion, and bromized
+collodion. Prof. Rowland and Captain Abney, R.E., are at present engaged
+in preparing a new map of the whole spectrum with a focus of 18 feet.
+
+In reply to Mr. Hilger, F.R.A.S., the author stated that if the metal is
+the true speculum metal used by Lord Rosse, it would stand the effects
+of climate, he thought; but if too much copper were put in, it might
+not.
+
+In reply to Mr. Warren de la Rue, Prof. Rowland said that 42,000 was the
+largest number of lines he had yet required to engrave on the metal.
+
+Prof. Guthrie read a letter from Captain Abney, pointing out that Prof.
+Rowland's plates gave clearer spectra than any others; they were free
+from "ghosts," caused by periodicity in the ruling, and the speculum
+metal had no particular absorption.
+
+Prof. Dewar, F.R.S., observed that Prof. Liveing and he had been engaged
+for three years past in preparing a map of the ultra-violet spectrum,
+which would soon be published. He considered the concave gratings to
+make a new departure in the subject, and that they would have greatly
+facilitated the preparation of his map.
+
+       *       *       *       *       *
+
+
+
+
+A NEW POCKET OPERA GLASS.
+
+
+[Illustration: POCKET OPERA GLASS.]
+
+Inasmuch as high power combined with small size is usually required in
+an opera glass, manufacturers have always striven to unite these two
+features in their instruments, and have succeeded in producing glasses
+which, although sufficiently small to be carried in the waistcoat
+pocket, are nevertheless powerful enough to allow quite distant objects
+to be clearly distinguished. Recently, a Parisian optician has succeeded
+in constructing an instrument of this kind that is somewhat of a novelty
+in its way, since its mechanism allows it to be closed in such a manner
+as to take up no more space than a package of cigarettes (Fig. 1.) It is
+constructed as follows:
+
+AB and CD (Fig. 1) are two metallic tubes, in which slide with slight
+friction two other tubes. Into the upper part of the latter are inserted
+two hollow elliptical eye-pieces, which move therein with slight
+friction, and which are united by the two supports tor the wheel, _bb_
+(Fig. 4), and endless screw that serve for focusing the instrument. The
+eyepieces, TT, are held in the tube by means of two screws, _vv_ (Figs.
+2 and 4), in such a way that they can revolve around the latter as axes.
+The lenses of the eye-piece are fixed therein by means of a copper ring.
+The object glasses are placed in the ends of the tubes, AB and CD, at
+_oo_.
+
+When the instrument is closed, it forms a cylinder 35 millimeters in
+diameter by 11 centimeters in length. To open it, it is grasped by the
+extremities and drawn apart horizontally so as to bring it into the
+position shown in Fig. 2. Then it is turned over so that the screw, V,
+points upward, while at the same time the two tubes are pressed gently
+downward. This causes the eye-pieces to revolve around their axes, _vv_,
+and brings the two tubes parallel with each other.--_La Nature._
+
+       *       *       *       *       *
+
+
+
+
+ANCIENT GREEK PAINTING.
+
+
+A lecture on ancient Greek painting was lately delivered by Professor
+C.T. Newton, C.B., at University College, London. The lecturer began by
+reminding his audience of the course of lectures on Greek sculpture,
+from the earliest times to the Roman period, which he completed this
+year. The main epochs in the history of ancient sculpture had an
+intimate connection with the general history of the Greeks, with their
+intellectual, political, and social development. We could not profitably
+study the history of ancient sculpture except as part of the collateral
+study of ancient life as a whole, nor could we get a clear idea of the
+history of ancient sculpture without tracing out, so far as our
+imperfect knowledge permits, the characteristics and successive stages
+of ancient painting. Between these twin sister arts there had been in
+all times, and especially in Greek antiquity, a close sympathy and a
+reciprocal influence. The method in dealing with the history of Greek
+painting in this course would be similar to that adopted in the course
+on sculpture. The evidence of ancient authors as to the works and
+characteristics of Greek painters would be first examined, then the
+extant monuments which illustrate the history of this branch of art
+would be described. In the case of painting, the extant monuments were
+few and far between, but we might learn much by the careful study of the
+mural paintings from the buried Campanian cities, Pompeii, Herculaneum,
+and those found in the tombs near Rome and Etruria. The paintings on
+Greek vases would enable us to trace the history of what is called
+ceramographic art from B.C. 600 for nearly five centuries onward.
+
+After noticing the traditions preserved by Pliny and others as to the
+earliest painters, the lecturer passed on to the period after the
+Persian war. Polygnotos of Thasos was the earliest Greek painter of
+celebrity. He flourished B.C. 480-460. At Athens he decorated with
+paintings the portico called the Stoa Poikile, the Temple of the
+Dioscuri, the Temple of Theseus, and the Pinakotheke on the Akropolis.
+At Delphi he painted on the walls of the building called Lesche two
+celebrated pictures, the taking of Troy and the descent of Ulysses into
+Hades. All these were mural paintings; the subjects were partly
+mythical, partly historical. Thus in the Stoa Poikile were represented
+the taking of Troy, the battle of Theseus with the Amazons, the battle
+of Marathon. In the Temple of Theseus came the battle of the Lapiths and
+Centaurs and the battle of the Amazons again. In the other two Athenian
+temples he treated mythological subjects. These great public works were
+executed during the administration of Kimon, to whom Polygnotos stood in
+the same relation us Phidias did to Perikles, the successor of Kimon.
+The paintings in the Stoa Poikile were executed by Polygnotos
+gratuitously, for which service the Athenians rewarded him with the
+freedom of their city. His greatest and probably his earliest works were
+the two pictures in the Lesche at Delphi. Of these there was a very full
+description in Pausanias. The building called Lesche was thought to have
+been of elliptical form, with a colonnade on either side, separated by a
+wall in the middle, and to have been about 90 ft in length. The figures
+were probably life size.
+
+According to the list given by Pausanias, there were upward of seventy
+in each of the two pictures. In that representing the taking of Troy
+Polygnotos had brought together many incidents described in the Cyclic
+epics: Menelaos Agamemnon, Ulysses, Nestor, Neoptolemos, Antenor, Helen,
+Andromache, Kassandra, and many other figures, with which the Homeric
+poems have made us familiar, all appeared united in one skillful
+composition, arranged in groups. The other picture, the descent of
+Ulysses into Hades to interrogate Teiresias, might be called a pictorial
+epic of Hades. On one side was the entrance, indicated by Charon's boat
+crossing: the Acheron, and the evocation of Teiresias by Ulysses,
+besides the punishment of Tityos and other wicked men; on the other side
+were Tantalos and Sisyphos. Between these scenes, on the flanks, were
+various groups of heroes and heroines from the Trojan and other legends.
+From the remarks of ancient critics, it might be inferred that the
+genius of Polygnotos, like that of Giotto, was far in advance of his
+technical skill. Aristotle called him the most ethical of painters, and
+recommended the young artist to study his works in preference to those
+of his contemporary Pauson, who was ignobly realistic, or those of
+Zeuxis, who had great technical merit, but was deficient in spiritual
+conception. The course will comprise four more lectures, as
+follows--November 17, "Greek Painters from B.C. 460 to Accession of
+Alexander the Great B.C. 336--Apollodoros, Zeuxis, Parrhasios,
+Pamphilos, Aristides;" November 24, "Greek Painters from Age of
+Alexander to Augustan Age--Apelles, Protogenes, Theon;" December 1,
+"Pictures on Greek Fictile Vases;" December 15, "Mural Paintings from
+Pompeii, Herculaneum, and other Ancient sites."
+
+       *       *       *       *       *
+
+
+The new Iowa State Capitol has thus far cost $2,000,000,
+and it will require $500,000 to finish it. It is 365 feet long
+fron north to south, and measures 274 feet from the sidewalk
+to the top of the central dome.
+
+       *       *       *       *       *
+
+[LONGMAN'S MAGAZINE.]
+
+
+
+
+ATOMS, MOLECULES, AND ETHER WAVES.
+
+By JOHN TYNDALL, F.R.S.
+
+
+I.
+
+Man is prone to idealization. He cannot accept as final the phenomena of
+the sensible world, but looks behind that world into another which rules
+the sensible one. From this tendency of the human mind, systems of
+mythology and scientific theories have equally sprung. By the former the
+experiences of volition, passion, power, and design, manifested among
+ourselves, were transplanted, with the necessary modifications, into an
+unseen universe from which the sway and potency of those magnified human
+qualities were exerted. "In the roar of thunder and in the violence of
+the storm was felt the presence of a shouter and furious strikers, and
+out of the rain was created an Indra or giver of rain." It is
+substantially the same with science, the principal force of which is
+expended in endeavoring to rend the veil which separates the sensible
+world from an ultra-sensible one. In both cases our materials, drawn
+from the world of the senses, are modified by the imagination to suit
+intellectual needs. The "first beginnings" of Lucretius were not objects
+of sense, but they were suggested and illustrated by objects of sense.
+The idea of atoms proved an early want on the part of minds in pursuit
+of the knowledge of nature. It has never been relinquished, and in our
+own day it is growing steadily in power and precision.
+
+The union of bodies in fixed and multiple proportions constitutes the
+basis of modern atomic theory. The same compound retains, for ever, the
+same elements, in an unalterable ratio. We cannot produce pure water
+containing one part, by weight, of hydrogen and nine of oxygen, nor can
+we produce it when the ratio is one to ten; but we can produce it from
+the ratio of one to eight, and from no other. So also when water is
+decomposed by the electric current, the proportion, as regards volumes,
+is as fixed as in the case of weights. Two volumes of hydrogen and one
+of oxygen invariably go the formation of water. Number and harmony, as
+in the Pythagorean system, are everywhere dominant in this under-world.
+
+Following the discovery of fixed proportions we have that of _multiple_
+proportions. For the same compound, as above stated, the elementary
+factors are constant; but one elementary body often unites with another
+so as to form different compounds. Water, for example, is an oxide of
+hydrogen; but a peroxide of that substance also exists, containing
+exactly double the quantity of oxygen. Nitrogen also unites with oxygen
+in various ratios, but not in all. The union takes place, not gradually
+and uniformly, but by steps, a definite weight of matter being added at
+each step. The larger combining quantities of oxygen are thus multiples
+of the smaller ones. It is the same with other combinations.
+
+We remain thus far in the region of fact: why not rest there? It might
+as well be asked why we do not, like our poor relations of the woods and
+forests, rest content with the facts of the sensible world. In virtue of
+our mental idiosyncrasy, we demand _why_ bodies should combine in
+multiple proportions, and the outcome and answer of this question is the
+atomic theory. The definite weights of matter, above referred to,
+represent the weights of atoms, indivisible by any force which chemistry
+has hitherto brought to bear upon them. If matter were a _continuum_--if
+it were not rounded off, so to say, into these discrete atomic
+masses--the impassable breaches of continuity which the law of multiple
+proportions reveals, could not be accounted for. These atoms are what
+Maxwell finely calls "the foundation stones of the material universe,"
+which, amid the wreck of composite matter, "remain unbroken and unworn."
+
+A group of atoms drawn and held together by what chemists term affinity
+is called a molecule. The ultimate parts of all compound bodies are
+molecules. A molecule of water, for example, consists of two atoms of
+hydrogen, which grasp and are grasped by one atom of oxygen. When water
+is converted into steam, the distances between the molecules are greatly
+augmented, but the molecules themselves continue intact. We must not,
+however, picture the constituent atoms of any molecule as held so
+rigidly together as to render intestine motion impossible. The
+interlocked atoms have still liberty of vibration, which may, under
+certain circumstances, become so intense as to shake the molecule
+asunder. Most molecules--probably all--are wrecked by intense heat, or
+in other words by intense vibratory motion; and many are wrecked by a
+very moderate heat of the proper quality. Indeed, a weak force, which
+bears a suitable relation to the constitution of the molecule, can, by
+timely savings and accumulations, accomplish what a strong force out of
+relation fails to achieve.
+
+We have here a glimpse of the world in which the physical philosopher
+for the most part resides. Science has been defined as "organized common
+sense;" by whom I have forgotten; but, unless we stretch unduly the
+definition of common sense, I think it is hardly applicable to this
+world of molecules. I should be inclined to ascribe the creation of that
+world to inspiration rather than to what is currently known as common
+sense. For the natural history sciences the definition may stand--hardly
+for the physical and mathematical sciences.
+
+The sensation of light is produced by a succession of waves which strike
+the retina in periodic intervals; and such waves, impinging on the
+molecules of bodies, agitate their constituent atoms. These atoms are so
+small, and, when grouped to molecules, are so tightly clasped together,
+that they are capable of tremors equal in rapidity to those of light and
+radiant heat. To a mind coming freshly to these subjects, the numbers
+with which scientific men here habitually deal must appear utterly
+fantastical; and yet, to minds trained in the logic of science, they
+express most sober and certain truth. The constituent atoms of molecules
+can vibrate to and fro millions of millions of times in a second. The
+waves of light and of radiant heat follow each other at similar rates
+through the luminiferous ether. Further, the atoms of different
+molecules are held together with varying degrees of tightness--they are
+tuned, as it were, to notes of different pitch. Suppose, then,
+light-waves, or heat-waves, to impinge upon an assemblage of such
+molecules, what may be expected to occur? The same as what occurs when a
+piano is opened and sung into. The waves of sound select the strings
+which respectively respond to them--the strings, that is to say, whose
+rates of vibration are the same as their own--and of the general series
+of strings these only sound. The vibratory motion of the voice, imparted
+first to the air, is here taken up by the strings. It may be regarded as
+_absorbed_, each string constituting itself thereby a new center of
+motion. Thus also, as regards the tightly locked atoms of molecules on
+which waves of light or radiant heat impinge. Like the waves of sound
+just adverted to, the waves of ether select those atoms whose periods of
+vibration synchronize with their own periods of recurrence, and to such
+atoms deliver up their motion. It is thus that light and radiant heat
+are absorbed.
+
+And here the statement, though elementary, must not be omitted, that the
+colors of the prismatic spectrum, which are presented in an impure form
+in the rainbow, are due to different rates of atomic vibration in their
+source, the sun. From the extreme red to the extreme violet, between
+which are embraced all colors visible to the human eye, the rapidity of
+vibration steadily increases, the length of the waves of ether produced
+by these vibrations diminishing in the same proportion. I say "visible
+to the human eye," because there may be eyes capable of receiving visual
+impression from waves which do not affect ours. There is a vast store of
+rays, or more correctly waves, beyond the red, and also beyond the
+violet, which are incompetent to excite our vision; so that could the
+whole length of the spectrum, visible and invisible, be seen by the same
+eye, its length would be vastly augmented.
+
+I have spoken of molecules being wrecked by a moderate amount of heat of
+the proper quality: let us examine this point for a moment. There is a
+liquid called nitrite of amyl--frequently administered to patients
+suffering from heart disease. The liquid is volatile, and its vapor is
+usually inhaled by the patient. Let a quantity of this vapor be
+introduced into a wide glass tube, and let a concentrated beam of solar
+light be sent through the tube along its axis. Prior to the entry of the
+beam, the vapor is as invisible as the purest air. When the light
+enters, a bright cloud is immediately precipitated on the beam. This is
+entirely due to the waves of light, which wreck the nitrite of amyl
+molecules, the products of decomposition forming innumerable liquid
+particles which constitute the cloud. Many other gases and vapors are
+acted upon in a similar manner. Now the waves that produce this
+decomposition are by no means the most powerful of those emitted by the
+sun. It is, for example, possible to gather up the ultra-red waves into
+a concentrated beam, and to send it through the vapor, like the beam of
+light. But, though possessing vastly greater energy than the light
+waves, they fail to produce decomposition. Hence the justification of
+the statement already made, that a suitable relation must subsist
+between the molecules and the waves of ether to render the latter
+effectual.
+
+A very impressive illustration of the decomposing power of the waves of
+light is here purposely chosen; but the processes of photography
+illustrate the same principle. The photographer, without fear,
+illuminates his developing room with light transmitted through red or
+yellow glass; but he dares not use blue glass, for blue light would
+decompose his chemicals. And yet the waves of red light, measured by the
+amount of energy which they carry, are immensely more powerful than the
+waves of blue. The blue rays are usually called chemical rays--a
+misleading term; for, as Draper and others have taught us, the rays that
+produce the grandest chemical effects in nature, by decomposing the
+carbonic acid and water which form the nutriment of plants, are not the
+blue ones. In regard, however, to the salts of silver, and many other
+compounds, the blue rays are the most effectual. How is it then that
+weak waves can produce effects which strong waves are incompetent to
+produce? This is a feature characteristic of periodic motion. In the
+experiment of singing into an open piano already referred to, it is the
+accord subsisting between the vibrations of the voice and those of the
+string that causes the latter to sound. Were this accord absent, the
+intensity of the voice might be quintupled, without producing any
+response. But when voice and string are identical in pitch, the
+successive impulses add themselves together, and this addition renders
+them, in the aggregate, powerful, though individually they may be weak.
+It some such fashion the periodic strokes of the smaller ether waves
+accumulate, till the atoms on which their timed impulses impinge are
+jerked asunder, and what we call chemical decomposition ensues.
+
+Savart was the first to show the influence of musical sounds upon liquid
+jets, and I have now to describe an experiment belonging to this class,
+which bears upon the present question. From a screw-tap in my little
+Alpine kitchen I permitted, an hour ago, a vein of water to descend into
+a trough, so arranging the flow that the jet was steady and continuous
+from top to bottom. A slight diminution of the orifice caused the
+continuous portion of the vein to shorten, the part further down
+resolving itself into drops. In my experiment, however, the vein, before
+it broke, was intersected by the bottom of the trough. Shouting near the
+descending jet produced no sensible effect upon it. The higher notes of
+the voice, however powerful, were also ineffectual. But when the voice
+was lowered to about 130 vibrations a second, the feeblest utterance of
+this note sufficed to shorten, by one half, the continuous portion of
+the jet. The responsive drops ran along the vein, pattered against the
+trough, and scattered a copious spray round their place of impact. When
+the note ceased, the continuity and steadiness of the vein were
+immediately restored. The formation of the drops was here periodic; and
+when the vibrations of the note accurately synchronized with the periods
+of the drops, the waves of sound aided what Plateau has proved to be the
+natural tendency of the liquid cylinder to resolve itself into
+spherules, and virtually decomposed the vein.
+
+I have stated, without proof, that where absorption occurs, the motion
+of the ether-waves is taken up by the constituent atoms of molecules. It
+is conceivable that the ether-waves, in passing through an assemblage of
+molecules, might deliver up their motion to each molecule as a whole,
+leaving the relative positions of the constituent atoms unchanged. But
+the long series of reactions, represented by the deportment of nitrite
+of amyl vapor, does not favor this conception; for, were the atoms
+animated solely by a common motion, the molecules would not be
+decomposed. The fact of decomposition, then, goes to prove the atoms to
+be the seat of the absorption. They, in great part, take up the energy
+of the ether-waves, whereby their union is severed, and the building
+materials of the molecules are scattered abroad.
+
+Molecules differ in stability; some of them, though hit by waves of
+considerable force, and taking up the motions of these waves,
+nevertheless hold their own with a tenacity which defies decomposition.
+And here, in passing, I may say that it would give me extreme pleasure
+to be able to point to my researches in confirmation of the solar theory
+recently enunciated by my friend the President of the British
+Association. But though the experiments which I have made on the
+decomposition of vapors by light might be numbered by the thousand, I
+have, to my regret, encountered no fact which prove that free aqueous
+vapor is decomposed by the solar rays, or that the sun is reheated by
+the combination of gases, in the severance of which it had previously
+sacrificed its heat.
+
+
+II.
+
+The memorable investigations of Leslie and Rumford, and the subsequent
+classical reasearches of Melloni, dealt, in the main, with the
+properties of radiant heat; while in my investigations, radiant heat,
+instead of being regarded as an end, was employed as a means of
+exploring molecular condition. On this score little could be said until
+the gaseous form of matter was brought under the dominion of experiment.
+This was first effected in 1859, when it was proved that gases and
+vapors, notwithstanding the open door which the distances between their
+molecules might be supposed to offer to the heat waves, were, in many
+cases, able effectually to bar their passage. It was then proved that
+while the elementary gases and their mixtures, including among the
+latter the earth's atmosphere, were almost as pervious as a vacuum to
+ordinary radiant heat, the compound gases were one and all absorbers,
+some of them taking up with intense avidity the motion of the
+ether-waves.
+
+A single illustration will here suffice. Let a mixture of hydrogen and
+nitrogen, in the proportion of three to fourteen by weight, be inclosed
+in a space through which are passing the heat rays from an ordinary
+stove. The gaseous mixture offers no measurable impediment to the rays
+of heat. Let the hydrogen and nitrogen now unite to form the compound
+ammonia. A magical change instantly occurs. The number of atoms present
+remains unchanged. The transparency of the compound is quite equal to
+that of the mixture prior to combination. No change is perceptible to
+the eye, but the keen vision of experiment soon detects the fact that
+the perfectly transparent and highly attenuated ammonia resembles pitch
+or lampblack in its behavior to the rays of heat.
+
+There is probably boldness, if not rashness, in the attempt to make
+these ultra-sensible actions generally intelligible, and I may have
+already transgressed the limits beyond which the writer of a familiar
+article cannot profitably go. There may, however, be a remnant of
+readers willing to accompany me, and for their sakes I proceed. A
+hundred compounds might be named which, like the ammonia, are
+transparent to light, but more or less opaque--often, indeed, intensely
+opaque--to the rays of heat from obscure sources. Now the difference
+between these latter rays and the light rays is purely a difference of
+period of vibration. The vibrations in the case of light are more rapid,
+and the ether waves which they produce are shorter, than in the case of
+obscure heat. Why, then, should the ultra-red waves be intercepted by
+bodies like ammonia, while the more rapidly recurrent waves of the whole
+visible spectrum are allowed free transmission? The answer I hold to be
+that, by the act of chemical combination, the vibrations of the
+constituent atoms of the molecules are rendered so sluggish as to
+synchronize with the motions of the longer waves. They resemble loaded
+piano strings, or slowly descending water jets, requiring notes of low
+pitch to set them in motion.
+
+The influence of synchronism between the "radiant" and the "absorbent"
+is well shown by the behavior of carbonic acid gas. To the complex
+emission from our heated stove, carbonic acid would be one of the most
+transparent of gases. For such waves olefiant gas, for example, would
+vastly transcend it in absorbing power. But when we select a radiant
+with whose waves the atoms of carbonic acid are in accord, the case is
+entirely altered. Such a radiant is found in a carbonic oxide flame,
+where the radiating body is really hot carbonic acid. To this special
+radiation carbonic acid is the most opaque of gases.
+
+And here we find ourselves face to face with a question of great
+delicacy and importance. Both as a radiator and as an absorber, carbonic
+acid is, in general, a feeble gas. It is beaten in this respect by
+chloride of methyl, ethylene, ammonia, sulphurous acid, nitrous oxide,
+and marsh gas. Compared with some of these gases, its behavior, in fact,
+approaches that of elementary bodies. May it not help to explain their
+neutrality? The doctrine is now very generally accepted that atoms of
+the same kind may, like atoms of different kinds, group themselves to
+molecules. Affinity exists between hydrogen and hydrogen and between
+chlorine and chlorine, as well as between hydrogen and chlorine. We have
+thus homogeneous molecules as well as heterogeneous molecules, and the
+neutrality so strikingly exhibited by the elements may be due to a
+quality of which carbonic acid furnishes a partial illustration. The
+paired atoms of the elementary molecules may be so out of accord with
+the periods of the ultra red waves--the vibrating periods of these atoms
+may, for example, be so rapid--as to disqualify them both from emitting
+those waves, and from accepting their energy. This would practically
+destroy their power, both as radiators and absorbers. I have reason to
+know that a distinguished authority has for some time entertained this
+hypothesis.
+
+We must, however, refresh ourselves by occasional contact with the solid
+ground of experiment, and an interesting problem now lies before us
+awaiting experimental solution. Suppose two hundred men to be scattered
+equably throughout the length of Pall Mall. By timely swerving now and
+then, a runner from St. James's Palace to the Athenæum Club might be
+able to get through such a crowd without much hinderance. But supposing
+the men to close up so as to form a dense file crossing Pall Mall from
+north to south; such a barrier might seriously impede, or entirely stop,
+the runner. Instead of a crowd of men, let us imagine a column of
+molecules under small pressure, thus resembling the sparsely distributed
+crowd. Let us suppose the column to shorten, without change in the
+quantity of matter, until the molecules are so squeezed together as to
+resemble the closed file across Pall Mall. During these changes of
+density, would the action of the molecules upon a beam of heat passing
+among them at all resemble the action of the crowd upon the runner?
+
+We must answer this question by direct experiment. To form our molecular
+crowd we place, in the first instance, a gas or vapor in a tube 38
+inches long, the ends of which are closed with circular windows,
+air-tight, but formed of a substance which offers little or no
+obstruction to the calorific waves. Calling the measured value of a heat
+beam passing through this tube 100, we carefully determine the
+proportionate part of this total absorbed by the molecules in the tube.
+We then gather precisely the same number of molecules into a column 10.8
+inches long, the one column being thus three and a half times the length
+of the other. In this case also we determine the quantity of radiant
+heat absorbed. By the depression of a barometric column, we can easily
+and exactly measure out the proper quantities of the gaseous body. It is
+obvious that one mercury inch of vapor, in the long tube, would
+represent precisely the same amount of matter--or, in other words, the
+same number of molecules--as 3½ inches in the short one; while 2
+inches of vapor in the long tube would be equivalent to 7 inches in the
+short one.
+
+The experiments have been made with the vapors of two very volatile
+liquids, namely, sulphuric ether and hydride of amyl. The sources of
+radiant heat were, in some cases, an incandescent lime cylinder, and in
+others a spiral of platinum wire, heated to bright redness by an
+electric current. One or two of the measurements will suffice for the
+purposes of illustration. First, then, as regards the lime light; for 1
+inch of pressure in the long tube, the absorption was 18.4 per cent. of
+the total beam; while for 3.5 inches of pressure in the short tube, the
+absorption was 18.8 per cent., or almost exactly the same as the former.
+For 2 inches pressure, moreover, in the long tube, the absorption was
+25.7 per cent.; while for 7 inches in the short tube it was 25.6 per
+cent. of the total beam. Thus closely do the absorptions in the two
+cases run together--thus emphatically do the molecules assert their
+individuality. As long as their number is unaltered, their action on
+radiant heat is unchanged. Passing from the lime light to the
+incandescent spiral, the absorptions of the smaller equivalent
+quantities, in the two tubes, were 23.5 and 23.4 per cent.; while the
+absorptions of the larger equivalent quantities were 32.1 and 32.6 per
+cent., respectively. This constancy of absorption, when the density of a
+gas or vapor is varied, I have called "the conservation of molecular
+action."
+
+But it may be urged that the change of density, in these experiments,
+has not been carried far enough to justify the enunciation of a law of
+molecular physics. The condensation into less than one-third of the
+space does not, it may be said, quite represent the close file of men
+across Pall Mall. Let us therefore push matters to extremes, and
+continue the condensation till the vapor has been squeezed into a
+liquid. To the pure change of density we shall then have added the
+change in the state of aggregation. The experiments here are more easily
+described than executed; nevertheless, by sufficient training,
+scrupulous accuracy, and minute attention to details, success may be
+insured. Knowing the respective specific gravities, it is easy, by
+calculation, to determine the condensation requisite to reduce a column
+of vapor of definite density and length to a layer of liquid of definite
+thickness. Let the vapor, for example, be that of sulphuric ether, and
+let it be introduced into our 38 inch tube till a pressure of 7.2 inches
+of mercury is obtained. Or let it be hydride of amyl, of the same
+length, and at a pressure of 6.6 inches. Supposing the column to
+shorten, the vapor would become proportionally denser, and would, in
+each case, end in the production of a layer of liquid exactly one
+millimeter in thickness.[1] Conversely, a layer of liquid ether or of
+hydride of amyl, of this thickness, were its molecules freed from the
+thrall of cohesion, would form a column of vapor 38 inches long, at a
+pressure of 7.2 inches in the one case, and of 6.6 inches in the other.
+In passing through the liquid layer, a beam of heat encounters the same
+number of molecules as in passing through the vapor layer: and our
+problem is to decide, by experiment, whether, in both cases, the
+molecule is not the dominant factor, or whether its power is augmented,
+diminished, or otherwise overridden by the state of aggregation.
+
+    [Footnote 1: The millimeter is 1-25th of an inch.]
+
+Using the sources of heat before mentioned, and employing diathermanous
+lenses, or silvered minors, to render the rays from those sources
+parallel, the absorption of radiant heat was determined, first for the
+liquid layer, and then for its equivalent vaporous layer. As before, a
+representative experiment or two will suffice for illustration. When the
+substance was sulphuric ether, and the source of radiant heat an
+incandescent platinum spiral, the absorption by the column of vapor was
+found to be 66.7 per cent. of the total beam. The absorption of the
+equivalent liquid layer was next determined, and found to be 67.2 per
+cent. Liquid and vapor, therefore, differed from each only 0.5 per
+cent.; in other words, they were practically identical in their action.
+The radiation from the lime light has a greater power of penetration
+through transparent substances than that from the spiral. In the
+emission from both of these sources we have a mixture of obscure and
+luminous rays; but the ratio of the latter to the former, in the lime
+light is greater than in the spiral; and, as the very meaning of
+transparency is perviousness to the luminous rays, the emission in which
+these rays are predominant must pass most freely through transparent
+substances. Increased transmission implies diminished absorption; and
+accordingly, the respective absorption of ether vapor and liquid ether,
+when the lime light was used, instead of being 66.7 and 67.2 per cent.,
+were found to be
+
+  Vapor....................33.3 per cent.
+  Liquid...................33.3   "
+
+no difference whatever being observed between the two states of
+aggregation. The same was found true of hydride of amyl.
+
+This constancy and continuity of the action exerted on the waves of heat
+when the state of aggregation is changed, I have called "the thermal
+continuity of liquids and vapors." It is, I think, the strongest
+illustration hitherto adduced of the conservation of molecular action.
+
+Thus, by new methods of search, we reach a result which was long ago
+enunciated on other grounds. Water is well known to be one of the most
+opaque of liquids to the waves of obscure heat. But if the relation of
+liquids to their vapors be that here shadowed forth, if in both cases
+the molecule asserts itself to be the dominant factor, then the
+dispersion of the water of our seas and rivers, as invisible aqueous
+vapor in our atmosphere, does not annul the action of the molecules on
+solar and terrestrial heat. Both are profoundly modified by this
+constituent; but as aqueous vapor is transparent, which, as before
+explained, means pervious to the luminous rays, and as the emission from
+the sun abounds in such rays, while from the earth's emission they are
+wholly absent, the vapor screen offers a far greater hinderance to the
+outflow of heat from the earth toward space than to the inflow from the
+sun toward the earth. The elevation of our planet's temperature is
+therefore a direct consequence of the existence of aqueous vapor in our
+air. Flimsy as that garment may appear, were it removed terrestrial life
+would probably perish through the consequent refrigeration.
+
+I have thus endeavored to give some account of a recent incursion into
+that ultra-sensible world mentioned at the outset of this paper. Invited
+by my publishers, with whom I have now worked in harmony for a period of
+twenty years, to send some contribution to the first number of their new
+Magazine, I could not refuse them this proof of my good will.
+
+J. TYNDALL
+
+Alp Lusgen, September 4, 1882
+
+       *       *       *       *       *
+
+
+The German empire has now about 34,000,000 acres of
+forest, valued at $400,000,000, and appropriates $500,000
+even year to increase and maintain the growth of trees.
+
+       *       *       *       *       *
+
+
+
+
+APPARATUS FOR MEASURING ELECTRICITY AT THE UPPER SCHOOL OF TELEGRAPHY.
+
+
+_Electro Tuning Forks and their Uses._--On a former occasion I described
+an instrument to which, in 1873, I gave the name _Electro-Tuning Fork_,
+and which is nothing else than a tuning fork whose motion is kept up
+electrically in such a way as to last indefinitely, provided that the
+elements of the pile are renewed gradually, and that from time to time
+the metallic contact is changed, which causes, at every oscillation, the
+current to pass from the pile into the magnet, which keeps up the
+vibration.
+
+We reproduce herewith, in Fig. 1, a cut showing in projection one of the
+simplest forms of the apparatus.
+
+[Illustration: FIG. 1.--CONSTANT VIBRATOR.]
+
+If we imagine the platinum or steel style, s, of the figure to be done
+away with, as well as the platinized plate, I, and its communication
+with the negative pole of the pile, P, we shall have the ordinary
+instrument kept in operation electrically by the aid of the
+electro-magnet, E, the style, s, the interrupting plate, I, and the
+pile.
+
+If we preserve the parts above mentioned, the instrument will possess
+the property of having vibrations of a constant amplitude if sufficient
+energy be kept up in the pile. In fact, when the amplitude is
+sufficiently great to cause the style, s, to touch the plate, I, it
+will be seen that at such a moment the current no longer passes through
+the electromagnet, and the vibration is no longer maintained. The
+amplitude cannot exceed an extent which shall permit the style, s, to
+touch I.
+
+Under such conditions, the duration of the vibrations remains exactly
+constant, as does also the vibratory intensity of the entire instrument.
+The measurement of time, then, by an instrument of this kind is, indeed,
+as perfect as it could well be.
+
+This complication in the arrangement of the apparatus has no importance
+as regards those tuning forks the number of whose vibrations exceeds a
+hundred per second, for in such a case these are given an amplitude of a
+few millimeters only; but it would be of importance with regard to
+instruments whose number of vibrations is very small, and to which it
+might be desirable to give great amplitude; for then, as I have long ago
+shown, the duration of the oscillation would depend a little on the
+amplitude, but a very little, it is true.
+
+I shall not refer now to the applications of these instruments in
+chronography, but will rather point out first the applications in which
+they are destined to produce an effective power.
+
+For this purpose it is necessary to make them pretty massive. The number
+of the vibrations depends upon such massiveness, and it is necessity to
+know the relation which exists between these two quantities in order to
+be able to construct an instrument under determinate conditions. I made
+in former years such a research with regard to tuning forks of prismatic
+form, that is to say, of a constant rectangular section continuing even
+into the bent portion where the parallel branches are united by a
+semicylinder, at the middle of which is the wrought iron rod as well as
+the branches. The _thickness_ of the instrument is the dimension
+parallel to the vibrations; its _width_ is the dimension which is
+perpendicular to them, and its _length_ is reckoned from the extremity
+of the branches up to the middle of the curved portion.
+
+It is found that the number of vibrations is independent of the width,
+proportional to the thickness, and very nearly inverse ratio of the
+square of the length, provided the latter exceeds ten centimeters.
+
+If we represent the length by l, the thickness by e, and the number
+of vibrations by n, we shall have the following formula:
+
+  n = k x ( e / l² )
+
+in which k is a constant quantity whose value depends upon the nature
+of the metal of which the tuning fork is made.
+
+This constant varies very little from steel to malleable cast iron, and
+it may be taken as equal to 818270.
+
+Thus, then, we have a means of constructing a tuning fork in which two
+of the three quantities, n, e, l, are given in advance. Experience
+proves that no errors are committed exceeding one or two per cent.
+
+It is seen from this that there is a means of increasing the mass of the
+instrument without changing anything in the thickness, the length or,
+consequently, the number of vibrations, and this is by increasing the
+_breadth_.
+
+It is in this way that I have succeeded in having long massive tuning
+forks made of malleable iron, giving no more than 12 to 15 vibrations
+per second, and vibrating with perfect regularity. Fig. 2, annexed,
+shows one of these instruments of about 55 centimeters length, whose
+breadth, E, is from 5 to 6 centimeters, and which makes about fifteen
+double vibrations per second only.
+
+[Illustration: FIG. 2.--THE ELECTRICAL TUNING FORK.]
+
+This number might be still further reduced, but at the expense of our
+being led to exaggerate the longitudinal dimensions of the apparatus in
+such a way as to make it inconvenient. The object may be attained more
+simply by loading the branches with slides supporting leaden weights, M,
+of 500 grammes each. By fixing these slides at different points on the
+branches, the number of vibrations can be made to vary from simple to
+double, and even triple. Thus, by fixing them at the extremity of the
+branches the number of the vibrations is reduced to 5 or 6.
+
+There will be seen in the figure the electro-magnet which keeps up the
+vibration. This is formed of three simple electro-magnets, whose bobbins
+have a resistance of no more than 10 ohms, and which are united in
+series. The interrupting plate, P, against which the style, s, rests
+at each vibration, is capable of a forward movement, or one of recoil,
+by the aid of a screw, V, and of an eccentric movement which is produced
+by a small handle, m, and during which its plane remains invariable.
+This arrangement permits the point of contact of the style and plate to
+be varied without changing the precision with which the contact takes
+place, and all the points of the plate to be slowly used in succession
+before replacing it. The motion is produced by means of a relatively
+weak pile, whose poles are connected to the terminals, A and A'. Three
+Callaud elements of triple surface, renewed one after the other every
+month at the most, are sufficient to keep up the vibrations
+continuously, day and night, without interruption, and that too even
+when the instrument is employed in producing a small mechanical power,
+as we shall see further on.
+
+We have now seen how electro-tuning forks may be constructed of large
+dimensions, of large mass, and giving a small number of vibrations per
+second.
+
+Such instruments are well fitted to perform the role of electrical
+interrupters, and it was in such a character that one of them figured in
+the Exhibition of the Upper School of Telegraphy as a type of an
+interrupter for testing piles.
+
+When it is desired to test a pile to ascertain the practicability of
+employing it in telegraphy, it is necessary to make it perform a work
+which shall be as nearly as possible identical with that which it will
+be called on to do, until it is used up, to estimate the duration of
+such work, to measure regularly the constants of the pile, the
+electro-motive power, and the internal resistance. Usually, in
+telegraphy, this work consists in sending over a line of a certain
+resistance intermittent currents, through the intermedium of suitable
+manipulators. It suffices then to cause the branches of the electro
+tuning fork to play the role of one of these manipulators. For doing
+this the tuning fork carries two insulating ebonite or ivory strips, B B
+(Fig. 3), which, at every oscillation, abut against vertical brass
+springs, r. Each of these latter is located in front of the platinized
+point of a screw, v, which is affixed to a small metallic tongue. The
+springs and tongues are insulated from each other, and are mounted on a
+piece which may be moved by a screw, V, so as to cause the springs of
+the strips, B B', to approach or recede according to the amplitude of
+the instrument's vibrations. Each spring and tongue is connected with
+terminals affixed to the base of the apparatus. One of the poles of one
+element, P, of the pile is connected with the tongue and corresponding
+screw, while the other pole is connected with the screw in front of it
+through the intermedium of a galvanometer, g², which gives the
+intensity of the intermittent current, and of a resistance coil,
+b², which performs the role of an artificial telegraph line. The
+apparatus being set in operation, it will be seen that the current from
+the pile is emitted once at every vibration.
+
+Thus there may be exhausted as many pile elements as there are springs,
+and that, too, simultaneously; and the contacts of the screws and
+springs can be regulated in such a way that the duration of the
+emissions shall be the same for all.
+
+At the laboratory of the School of Telegraphy one of these instruments
+has operated without interruption, day and night, during eighteen
+months.
+
+[Illustration: FIG. 4.--VERY RAPID ELECTRIC TUNING FORK]
+
+The apparatus shown in Fig. 4 is also an interrupting electro-tuning
+fork, but it makes a much greater number of vibrations than the
+preceding, and may serve for other electric tests.
+
+The operation of the tuning fork is kept up electrically by the aid of
+the screw, v, and the corresponding plate; of the style, s, and of
+the fine wire spiral spring, f, both insulated from the fork, from the
+electro-magnet, N, and from the two wires, F F', which communicate with
+a pile.
+
+The interrupting system is symmetrical with the first. It consists of
+the style, s, of the spiral spring, f, of the screw, v, and of the
+plate that this carries at its extremity. The terminal, B, which carries
+the spring, f, and the rod which carries the screw being insulated
+from each other, it is only necessary to cause to terminate therein the
+extremities of a circuit comprising one pile, in order to produce in the
+circuit a number of interruptions equal to that of the tuning fork's
+vibrations. Provided the lengths of the springs, f and _f'_, are
+proper, such vibrations will not be altered.
+
+Moreover, the instrument is so arranged as to produce vibrations whose
+_duration can be varied at pleasure and kept constant_ during the whole
+time the experiments last. This is done by modifying the _amplitude_ of
+the vibrations; for the greater the amplitude, the longer likewise the
+duration of the contact of the style, s, on the corresponding plate,
+and the shorter the duration of the interruption. In order to modify the
+amplitude, the action of the electro-magnet on the branches of the
+apparatus is made to vary. To effect this, the electro-magnet is made
+movable perpendicularly by the aid of a screw, V, between two slides, so
+that the core, N, may be moved with respect to the median line of the
+branches, and even be raised above them. Its action diminishes,
+necessarily, while it is being raised, and the amplitude of the
+vibrations likewise diminishes gradually and continuously. It may thus
+be made, without difficulty, to vary from two to three tenths of a
+millimeter to three or four millimeters or more.
+
+But it is not sufficient to cause the amplitude to vary; it is necessary
+to measure it and to keep it constant at the value desired.
+
+[Illustration: FIG. 5]
+
+The measurement is effected by the aid of a very simple apparatus that I
+have before described under the name of the _vibrating micrometer_. This
+is a small square of paper carrving a design like that shown in Fig. 5,
+and which is seen in Fig. 4 glued to one of the masses, M, which serve
+to vary the number of the instrument's vibrations. This figure is in
+fact, an angle, one of whose sides is graduated into millimeters, for
+example, and the other forms the edge of a wide black band. The apex of
+the angle is above and the divided side is perpendicular to the
+direction of the vibrations.
+
+Under such conditions, when the fork is vibrating, the apex of the
+angle, by virtue of the persistence of impressions upon the retina,
+_seems_ to advance along the graduation in measure as the amplitude of
+the vibrations increases. If an angle has been drawn such that the slope
+of one of its sides to the other is one-tenth, it is easy to see that
+for each millimeter passed over _apparently_ by the apex of the angle,
+the amplitude will increase by two-tenths of a millimeter.
+
+This is the way, then, that the amplitude is measured. On another hand,
+it suffices to keep the apex of the angle of the micrometer immovable,
+in order to be sure of the constancy of the tuning fork's amplitude; and
+this is done, when necessary, by causing the screw, V, to move slightly.
+
+The instrument represented in Fig. 4 is, moreover, fixed to a support
+devised by Mr. A. Duboscq, so as to make it possible to give the tuning
+fork every position possible with respect to a vertical plane; to raise
+it or lower it, and to move it backward or forward so that it may be
+employed for chimography, and in all those experiments in which
+electro-tuning folks are used.
+
+E. MERCADIER.
+
+       *       *       *       *       *
+
+
+
+
+LONGMAN'S MAGAZINE.
+
+OUR ORIGIN AS A SPECIES.
+
+By RICHARD OWEN, C.B., F.R.S.
+
+
+There seems to be a manifest desire in some quarters to anticipate the
+looked for and, by some, hoped-for proofs of our descent, or rather
+ascent, from the ape.
+
+In the September issue of the _Fortnightly Review_ a writer cites, in
+this relation, the "Neanderthal skull, which possesses large bosses on
+the forehead, strikingly suggestive of those which give the gorilla its
+peculiarly fierce appearance;" and he proceeds: "No other human skull
+presents so utterly bestial a type as the Neanderthal fragment. If one
+cuts a female gorilla-skull in the same fashion, the resemblance is
+truly astonishing, and we may say that the only human feature in the
+skull is its size."[1]
+
+    [Footnote 1: Grant Allen, "On Primitive Man," p. 314.]
+
+In testing the question as between Linnæus and Cuvier of the zoological
+value of the differences between lowest man and highest ape, a
+naturalist would not limit his comparison of a portion of the human
+skull with the corresponding one of a female ape, but would extend it to
+the young or immature gorilla, and also to the adult male; he would then
+find the generic and specific characters summed up, so far, at least, as
+a portion or "fragment" of the skull might show them. What is posed as
+the "Neanderthal skull" is the roof of the brain-case, or "calvarium" of
+the anatomist, including the pent-house overhanging the eye-holes or
+"orbits." There is no other part of the fragment which can be supposed
+to be meant by the "large bosses" of the above quotation. And, on this
+assumption, I have to state that the super-orbital ridge in the
+calvarium in question is but little more prominent than in certain human
+skulls of both higher and lower races, and of both the existing and
+cave-dwelling periods. It is a variable cranial character, by no means
+indicative of race, but rather of sex.
+
+Limiting the comparison to that on which the writer quoted bases his
+conclusions--apparently the superficial extent of the roof plate--its
+greater extent as compared with that of a gorilla equaling, probably, in
+weight the entire frame of the individual from the Neanderthal cave, is
+strongly significant of the superiority of size of brain in the
+cave-dweller. The inner surface moreover indicates the more complex
+character of the soft organ on which it was moulded; the precious "gray
+substance" being multiplied by certain convolutions which are absent in
+the apes. But there is another surface which the unbiased zoologist
+finds it requisite to compare. In the human "calvarium" in question, the
+mid-line traced backward from the super-orbital ridge runs along a
+smooth track. In the gorilla a ridge is raised from along the major part
+of that tract to increase the surface giving attachment to the biting
+muscles. Such ridge in this position varies only in height in the female
+and the male adult ape, as the specimens in the British Museum
+demonstrate. In the Neanderthal individual, as in the rest of mankind,
+the corresponding muscles do not extend their origins to the upper
+surface of the cranium, but stop short at the sides forming the inner
+wall or boundary of what are called the "temples," defined by Johnson as
+the "upper part of the sides of the head," whence our "biting muscles"
+are called "temporal," as the side-bones of the skull to which they are
+attached are also the "temporal bones." In the superficial comparison to
+which Mr. Grant Allen has restricted himself in bearing testimony on a
+question which perhaps affects our fellow-creatures, in the right sense
+of the term, more warmly than any other in human and comparative
+anatomy, the obvious difference just pointed out ought not to have been
+passed over. It was the more incumbent on one pronouncing on the
+paramount problem, because the "sagittal ridge in the gorilla," as in
+the orang, relates to and signifies the dental character which
+differentiates all _Quadrumana_ from all _Bimana_ that have ever come
+under the ken of the biologist. And this ridge much more "strikingly
+suggests" the fierceness of the powerful brute-ape than the part
+referred to as "large bosses." Frontal prominences, more truly so
+termed, are even better developed in peaceful, timid, graminivorous
+quadrupeds than in the skulls of man or of ape. But before noticing the
+evidence which the teeth bear on the physical relations of man to brute,
+I would premise that the comparison must not be limited to a part or
+"fragment" of the bony frame, but to its totality, as relating to the
+modes and faculties of locomotion.
+
+Beginning with the skull--and, indeed, for present aim, limiting myself
+thereto--I have found that a vertical longitudinal section brings to
+light in greatest number and of truest value the differential characters
+between lowest _Homo_ and highest _Simia_. Those truly and indifferently
+interested in the question may not think it unworthy their time--if it
+has not already been so bestowed--to give attention to the detailed
+discussions and illustrations of the characters in question in the
+second and third volumes of the "Transactions of the Zoological
+Society."[2] The concluding memoir, relating more especially to points
+of approximation in cranial and denial structure of the highest
+_Quadrumane_ to the lowest _Bimane_, has been separately published.
+
+    [Footnote 2: "Oseteological Contributions to the Natural History
+    of the Orangs (_Pithecus_) and Chimpanzees (_Troglodites niger_
+    and _Trog. gorilla_)."]
+
+I selected from the large and instructive series of human skulls of
+various races in the Museum of the Royal College of Surgeons that which
+was the lowest, and might be called most bestial, in its cranial and
+dental characters. It was from an adult of that human family of which
+the life-characters are chiefly but truly and suggestively defined in
+the narrative of Cook's first voyage in the Endeavor.[3]
+
+    [Footnote 3: Hawkesworth's 4th ed., vol. iii., 1770, pp. 86,
+    137, 229. The skull in question is No 5,394 of the "Catalogue of
+    the Osteology" in the above Museum, 4to, vol. ii, p. 823, 1853.]
+
+Not to trespass further on the patience of my readers, I may refer to
+the "Memoir on the Gorilla," 4to, 1865. Plate xii. gives a view, natural
+size, of the vertical and longitudinal section of an Australian skull;
+plate xi. gives a similar view of the skull of the gorilla. Reduced
+copies of these views may be found at p. 572, figs. 395, 396, vol. ii,
+of my "Anatomy of Vertebrates."
+
+As far as my experience has reached, there is no skull displaying the
+characters of a quadrumanous species, as that series descends from the
+gorilla and chimpanzee to the baboon, which exhibits differences, osteal
+or dental, on which specific and generic distinctions are founded, so
+great, so marked, as are to be seen, and have been above illustrated, in
+the comparison of the highest ape with the lowest man.
+
+The modification of man's upper limbs for the endless variety, nicety,
+and perfection of their application, in fulfillment of the behests of
+his correspondingly developed brain--actions summed up in the term
+"manipulation"--testify as strongly to the same conclusion. The
+corresponding degree of modification of the human lower limbs, to which
+he owes his upright attitude, relieving the manual instruments from all
+share in station and terrestrial locomotion--combine and concur in
+raising the group so characterized above and beyond the apes, to, at
+least, ordinal distinction. The dental characters of mankind bear like
+testimony. The lowest (Melanian), like the highest (Caucasian), variety
+of the bimanal order differs from the quadrumanal one in the order of
+appearance, and succession to the first set of teeth, of the second or
+"permanent" set. The foremost incisor and foremost molar are the
+earliest to appear in that scries; the intermediate teeth are acquired
+sooner than those behind the foremost molar.[4]
+
+    [Footnote 4: "Odontography," 4to, 1840-44, p. 454, plates 117,
+    118, 119.]
+
+In the gorilla and chimpanzee, the rate or course of progress is
+reversed; the second true molar, or the one behind the first, makes its
+appearance before the bicuspid molars rise in front of the first; and
+the third or last of the molars behind the first comes into place before
+the canine tooth has risen. This tooth, indeed, which occupies part of
+the interval between the foremost incisor and foremost molar, is the
+last of the permanent set of teeth to be fully developed in the
+_Quadrumana_; especially in those which, in their order, rank next to
+the _Bimana_. To this differential character add the breaks in the
+dental series necessitated for the reception of the crowns of the huge
+canines when the gorilla or chimpanzee shuts its mouth.
+
+But the superior value of developmental over adult anatomical characters
+in such questions as the present is too well known in the actual phase
+of biology to need comment.
+
+In the article on "Primeval Man," the author states that the Cave-men
+"probably had lower foreheads, with high bosses like the Neanderthal
+skull, and big canine teeth like the Naulette jaw."[5]
+
+    [Footnote 5: _Fortnightly Review_, September, p. 321.]
+
+The human lower jaw so defined, from a Belgian cave, which I have
+carefully examined, gives no evidence of a canine tooth of a size
+indicative of one in the upper jaw necessitating such vacancy in the
+lower series of teeth which the apes present. There is no such vacancy
+nor any evidence of a "big canine tooth" in that cave specimen. And,
+with respect to cave specimens in general, the zoological characters of
+the race of men they represent must be founded on the rule, not on an
+exception, to their cranial features. Those which I obtained from the
+cavern at Bruniquel, and which are now exhibited in the Museum of
+Natural History, were disinterred under circumstances more
+satisfactorily determining their contemporaneity with the extinct
+quadrupeds those cave-men killed and devoured than in any other spelæan
+retreat which I have explored. They show neither "lower foreheads" nor
+"higher bosses" than do the skulls of existing races of mankind.
+
+Present evidence concurs in concluding that the modes of life and grades
+of thought of the men who have left evidences of their existence at the
+earliest periods hitherto discovered and determined, were such as are
+now observable in "savages," or the human races which are commonly so
+called.
+
+The industry and pains now devoted to the determination of the physical
+characters of such races, to their ways of living, their tools and
+weapons, and to the relations of their dermal, osteal, and dental
+modifications to those of the mammals which follow next after _Bimana_
+in the descensive series of mammalian orders, are exemplary.
+
+The present phase of the quest may be far from the bourn to yield
+hereafter trustworthy evidence of the origin of man; but, meanwhile,
+exaggerations and misstatements of acquired grounds ought especially to
+be avoided.
+
+       *       *       *       *       *
+
+
+
+
+THE ABA OR ODIKA.
+
+By W.H. BACHELER, M.D.
+
+
+Among the many luxuriant and magnificent forest trees of equatorial West
+Africa, none can surpass, for general beauty and symmetry, that which is
+called by the natives the "aba." When growing alone and undisturbed, its
+conical outline and dark green foliage remind one very much of the white
+maples of the northern United States, by a distant view, but, on a
+nearer approach, a dissimilarity is observed. Wherever, in ravines or
+near the banks of rivers, the soil is moist the most part of the year,
+there the aba chooses to grow, and during the months of June and July
+the falling fruits permeate the atmosphere with a delicious fragrance
+not similar to any other. This, in form, size, and general appearance,
+is very much like mango apples, so that the natives call mangoes the
+"white man's aba;" but the wild aba is not much eaten as a fruit, one or
+two being sufficient for the whole season. The kernel, or seed, is the
+important and useful part.
+
+When the fallen fruit covers the ground, much as apples do in America,
+the natives go in canoes to gather it, and the number harvested will be
+in proportion to the industry of the women. The aba plum is about the
+size of a goose's egg, of a flattened, ovoid shape, and, when ripe, a
+beautiful golden color. It consists of three distinct parts: the rind,
+the pulp, and the seed. The pulp consists of a mass extensively
+interwoven with strong filaments, which apparently grow out of the seed
+and are with great difficulty separated from it. The seed, reniform in
+shape, is bivalved, and constitutes about two-thirds of the bulk of the
+entire plum, and the inner kernel two-thirds the bulk of the seed.
+
+In consequence of it being such a high tree and growing in such
+inconvenient places, I have been unable to procure a specimen of the
+flowers.
+
+As soon as the fruit is brought to the village, all the inhabitants
+assemble with cutlasses and engage in the work of opening the plums and
+removing the kernels. The former are thrown away as useless. The seeds
+are evenly spread on the top of a rack of small sticks, under which a
+fire is built in the morning, and subjected to the smoke and heat of an
+entire day. Toward evening the heat is greatly augmented, and in a
+couple of hours the process is completed. The kernels are now soft, and
+the oil oozing from them, and while yet in this condition they are
+thrown into an immense trough and throughly beaten and mashed with a
+pestle.
+
+Baskets, with banana leaves spread in the inside to prevent the escape
+of the product, are in readiness, and it is put into them and pressed
+down. The next day these baskets are suspended in the sun, and at night
+are brought into the houses to congeal. The process is now finished. The
+cakes are removed by inversion of the baskets and "bushrope" tied around
+them, by which the pieces are carried. As thus prepared, odika is highly
+esteemed by the natives as an article of food, being made into a kind of
+thick gravy and eaten with boiled plantains.
+
+While at an interior mission station on the Ogowe River, I made some
+experiments in soap making. With palm oil I succeeded very well, using
+for an alkali the old-fashioned lye of ashes. But I was disappointed
+with the odika, though I learned some peculiar characteristics of it as
+a grease. By boiling the crude odika, I was unable, as I hoped, to
+separate the oleaginous from the extraneous matter, of which it contains
+a large proportion, but when the above-mentioned lye was used instead of
+water, the mass, instead of saponifying, merely separated; the grease,
+resembling very much in all particulars ordinary beef tallow, rising to
+the top of the caldron, while the refuse was precipitated.
+
+After clarifying this, it answers instead of oil of theobroma very
+nicely, and I have used it considerably in making ointments and
+suppositories with pleasing results.
+
+Gaboon, W. Africa, Aug., 1882.--_New Remedies._
+
+       *       *       *       *       *
+
+
+
+
+CALIFORNIA CEDARS.
+
+
+The incense cedar (_Libocedius decurrens_) is one of the valued trees of
+the California coast and mountains. It is eminently noted for great
+rapidity of growth, wonderful lightness, stiffness, and extraordinary
+durability. A thousand uses have sprung up and are multiplying around
+this interesting cedar as its most inestimable qualities become better
+known. Fortunately it is one of the most extensively distributed trees
+of the Pacific--found from the coast range north, south to San Diego,
+Sierra Nevada, southern Oregon, and most of the interior mountain region
+from 2,000 to 4,000 feet, and it even thrives quite well at 6,600 feet
+altitude, but seeming to give out at 7,000 feet, though said to extend
+to 8,500 feet, which is questionable. As usual with the sylva, flora,
+and fauna, this also is found lowest along the coast, where it finds the
+requisite temperature and other essentials, with combined moisture. The
+base and lower trunk somewhat resembles the Western juniper (_J.
+occidentalis_). It is to be noted in general that trees of such broad,
+outwardly sweeping, or expanded bases seldom blow over, and to the
+perceptive and artistic eye their significant character is one of
+firmness and stability. One hundred to two hundred feet high, six to
+nine feet in diameter (rarely larger) the shaft is often clear of limbs
+80 to 100 feet, and although the lower limbs, or even dry branches, may
+encumber the middle portion, pin-knots do not damage the timber. The
+massive body tapers more rapidly above than redwood, and is less
+eccentric than juniper, yet its general port resembles most the best
+specimens of the latter. The light cinnamon bark is thick and of
+shreddy-fibered texture, but so concretely compacted as to render the
+surface evenly ridged by very long, big bars of bark. These sweep
+obliquely down on the long spiral twist of swift water lines. The top is
+conic, the foliage is in compressed, flattened sprays, upright,
+thickened, and somewhat succulent; if not a languid type, at least in no
+sense rigid. It bears some resemblance to the great Western arborvitæ
+(_Thuja gigantea_), but the tiny leaf-scales are opposite and quite
+awl-pointed. The general hue of the foliage is light yellowish green,
+warmly tinted, golden and bead tipped, with tiny, oblong male catkins,
+as the fruit ripens in October and November. The cones are pendulous
+from the tips of twigs, oblong, and seldom over three-quarters of an
+inch long, little more than one-third as thick, and for the most part a
+trifle compressed. The wood is a pale cream-tint in color--a delicate
+salmon shade. This would hardly warrant the name white cedar, sometimes
+applied to it, as well as the giant arborvitæ. The extreme lightness of
+the lumber and its sweetness for packing boxes will commend it for
+express and commercial purposes, for posts and fencing, and especially
+railway ties, for sleepers, stringers, and ground timbers of all
+varieties, and for unnumbered uses, a tithe of which cannot be told in a
+brief notice. Formerly these trees were cut away and burned up, to clear
+the track for redwood, tamarack, and ponderous pith-pines, etc.; now all
+else is superseded by this incense cedar. Thus is seen how hasty and
+ill-advised notions give place to genuine merit.
+
+A fungus (_dædalus_) attacks and honeycombs it; and riddled as it may
+occasionally be, still, if spike or nail finds substance enough to hold,
+or sufficient solidity to resist crushing, then, for many purposes, even
+such lumber is practically as good as the soundest timber; because when
+the tree dies the fungus dies, and thenceforth will absorb no more
+moisture than the soundest part, and is alike imperishable, contrary to
+common experience in similar cases. This is a timber nearly as lasting
+as solid granite. For ship or boat lumber, the clear stuff from sound
+wood is so exceedingly light, stiff, and durable, and so plenty and
+available, that few timbers excel it, unless the yellow cedar or cyprus
+(_Cupressus nutkaensis_) is excepted, which is a little tougher,
+stronger, perhaps more elastic, and equally durable, if judged apart
+from thorough tests and careful data, which, it has been remarked, the
+apathy or ignorance of some governments appear to deem unworthy their
+sublime attention. There are said to be in California a thousand times
+more and better kinds of naval timbers on government lands as important
+to preserve as the live oaks of the South Atlantic States. It has been
+asserted as probable that, after due investigation, California would be
+found to possess a vast amount of the best naval timber in the world, a
+hundredfold more lasting than the best now in use, if a few woods are
+excepted, of which there is understood to be no very adequate supply.
+
+The great Washington cedar (_Sequoia gigantea_) is another important
+California tree. The great sequoian timber belt lies along the Sierras,
+upon the first exposed mountain side--moraines of recent retiring
+glaciers--that face the Pacific, from Calaveras on the north to near the
+head of Deer Creek on the south--a distance of 200 miles, or a little
+above 38 degrees north to a little below 36 degrees; altitude 5,000 to
+8,000 feet, and rarely 8,400 feet. The belt is broken by two gaps, each
+40 miles wide, caused by manifest topographical and glacial reasons, one
+gap between Calaveras and Tuolumne, the other between Fresno and King's
+River; thence the vast forest trends south, across the broad basins of
+Kaweah and Tule, a distance of 70 miles, on fresh moraine soil, ground
+from high mountain flanks by glaciers. The inscriptions are scarcely
+marred by post glacial agents, and the contiguous water-worn marks are
+often so slight in the rock-bound streams as to be measured by a few
+inches. Rarely does one of these sound and vigorous cedars fall, and
+those that do will lie 800 to 1,000 years, scarcely less perishable than
+the granite on which they grew. The great sequoian ditches, dug at a
+blow by their fall, and the tree tumuli, always turned up beside the
+deep root-bowls, remain; but, scientists assert, not a vestige of one
+outside the present forests has yet presented itself, hence the area has
+not been diminished during the last 8,000 or 10,000 years, and probably
+not at all in post glacial times. These colossal sequoias rise 275, 300,
+and even 400 feet aloft; are 20 to 30, and in some rare cases 40 feet in
+diameter, looking like vast columnar pillars of the skies. No known
+trees of the world compare with them and their kin, the redwoods, for
+the focused proximity of such a marvelous amount of timber within
+limited areas--as it were, the highest standard of timber-land capacity.
+The stage coach passes through one; 120 children and a piano crowd
+inside another; a trunk furnishes a house for cotillon parties to dance
+"stout on stumps;" a horse and rider travel within the burnt-out hollows
+of others, and so on. A single tree would furnish a two-rail fence, 20
+to 30 miles long. The tree has great value for wood and lumber.--_N.W.
+Lumberman._
+
+       *       *       *       *       *
+
+
+A catalogue containing brief notices of many important
+scientific papers heretofore published in the SUPPLEMENT,
+may be had gratis at this office.
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+End of the Project Gutenberg EBook of Scientific American Supplement, No.
+365, December 30, 1882, by Various
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